user17624: Elaboration:: 
There seems to be a relation between daily-life behaviour of a person and movements associated with his private parts. 
These movements can be internal, can be external. Eg. are hardening during sleep, release of harmones(knowingly or unknowingly). Even the fluctuations in hardness seems to depict deep thoughts-with-behaviour of person, like egoistic speech, greedy thinking pattern etc.... whose stored force(in form of sankharas, probably) gives fluctuations in hardness.
I tried to find on internet, couldn't find. Are there any chapters dealing with such knowledge in tipitaka(of any tradition)? 
(this time, it's not a challenge, rather a query.)

user8157: 
When it is stiff because of sensual desire: for one oppressed by
  sensual desire, the penis becomes erect.
When it is stiff due to feces: for one oppressed by feces, the penis
  becomes erect.
When it is stiff due to urine:for one oppressed by urine, the penis
  becomes erect.
When it is stiff because of wind: for one oppressed by wind, the penis
  becomes erect.
When it is stiff because of being bitten by caterpillars: when bitten
  by caterpillars, the penis becomes erect.
https://suttacentral.net/pli-tv-bu-vb-ss1/en/brahmali


user12677: In this, I'm not discussing any particular attainment, but:
After 50 odd years practising Theravada, including some 20 odd years in a Forest environment, during which there was the endless fear of erection, I unwittingly developed techniques for reversing the energy flow back to the origin of sensation, based on [mis]conceptions of Kundalini.  The upshot of which is that whilst recently having returned to lay status and thus permitted relationships in accord with the third precept -  Kamesu micchacara - I am now permanently incapable of erection.

user11009: 
There is evidence that an arahant has undergone such transformation in body
  chemistry that he has gone beyond the dichotomy of masculinity and femininity. All
  normal physiological sexual functions seem to be atrophied in an arahant as it is said
  that seminal emission is impossible for an arahant even in sleep.32 We may also note
  the tradition maintaining that arahants never dream,33 maybe because they have attained
  such perfect mental health that there is no necessity to release tension through dreams.

Nibbåna As Living Experience (Lily de Silva)

The footnote is a reference to the Vinaya, in the section "allowance for a sitting-cloth (Vin 1.295)":

Thus it is, Ānanda, thus it is, Ānanda, that when they fell asleep, thoughtless, careless, impurity was emitted as the result of a dream. Ānanda, those monks who fall asleep calling up mindfulness, careful, by these impurity is not emitted; and, Ānanda, those who are ordinary people, passionless in regard to pleasures of the senses, by these impurity is not emitted. It is impossible, it cannot come to pass, Ānanda, that impurity should be emitted by one perfected.”


17624: <p>Elaboration:: </p>

<p>There seems to be a relation between daily-life behaviour of a person and movements associated with <strong>his</strong> private parts. </p>

<p>These movements can be internal, can be external. Eg. are hardening during sleep, release of harmones(knowingly or unknowingly). Even the fluctuations in hardness seems to depict deep thoughts-with-behaviour of person, like egoistic speech, greedy thinking pattern etc.... <strong>whose stored force(in form of sankharas, probably) gives fluctuations in hardness</strong>.</p>

<p>I tried to find on internet, couldn't find. <strong>Are there any chapters dealing with such knowledge in tipitaka(of any tradition)?</strong> </p>

<p><em>(this time, it's not a challenge, rather a query.)</em></p>
 8157: <blockquote>
  <p>When it is stiff because of sensual desire: for one oppressed by
  sensual desire, the penis becomes erect.</p>
  
  <p>When it is stiff due to feces: for one oppressed by feces, the penis
  becomes erect.</p>
  
  <p>When it is stiff due to urine:for one oppressed by urine, the penis
  becomes erect.</p>
  
  <p>When it is stiff because of wind: for one oppressed by wind, the penis
  becomes erect.</p>
  
  <p>When it is stiff because of being bitten by caterpillars: when bitten
  by caterpillars, the penis becomes erect.</p>
  
  <p><a href="https://suttacentral.net/pli-tv-bu-vb-ss1/en/brahmali" rel="nofollow noreferrer">https://suttacentral.net/pli-tv-bu-vb-ss1/en/brahmali</a></p>
</blockquote>
 12677: <p>In this, I'm not discussing any particular attainment, but:
After 50 odd years practising Theravada, including some 20 odd years in a Forest environment, during which there was the endless fear of erection, I unwittingly developed techniques for reversing the energy flow back to the origin of sensation, based on [mis]conceptions of Kundalini.  The upshot of which is that whilst recently having returned to lay status and thus permitted relationships in accord with the third precept -  Kamesu micchacara - I am now permanently incapable of erection.</p>
 11009: <blockquote>
  <p>There is evidence that an arahant has undergone such transformation in body
  chemistry that he has gone beyond the dichotomy of masculinity and femininity. All
  normal physiological sexual functions seem to be atrophied in an arahant as it is said
  that seminal emission is impossible for an arahant even in sleep.32 We may also note
  the tradition maintaining that arahants never dream,33 maybe because they have attained
  such perfect mental health that there is no necessity to release tension through dreams.</p>
  
  <p><a href="https://i.stack.imgur.com/1OAzT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1OAzT.png" alt="enter image description here"></a></p>
  
  <p><a href="https://www.accesstoinsight.org/lib/authors/desilva/wheel407.pdf" rel="nofollow noreferrer">Nibbåna As Living Experience (Lily de Silva)</a></p>
</blockquote>

<p>The footnote is a reference to the Vinaya, in the section "<a href="https://suttacentral.net/pli-tv-kd8/en/horner-brahmali" rel="nofollow noreferrer">allowance for a sitting-cloth (Vin 1.295)</a>":</p>

<blockquote>
  <p>Thus it is, Ānanda, thus it is, Ānanda, that when they fell asleep, thoughtless, careless, impurity was emitted as the result of a dream. Ānanda, those monks who fall asleep calling up mindfulness, careful, by these impurity is not emitted; and, Ānanda, those who are ordinary people, passionless in regard to pleasures of the senses, by these impurity is not emitted. It is impossible, it cannot come to pass, Ānanda, that impurity should be emitted by one perfected.”</p>
</blockquote>
