referring to fig1 to 3 , the first embodiment 10 of the novelty writing instrument of the present invention is illustrated . as shown in fig1 embodiment 10 has a plastic body member 12 which has an upper tapered end 14 and a lower , generally cylindrical end 16 . a conventional writing mechanism 18 ( only the top of which is shown ), e . g ., pencil , ballpoint , felt - tip or ink pen mechanism , is housed within the body member 12 . if desired the juncture between the upper and lower ends 14 and 16 may be discontinuous or stepped ( as indicated by the line 20 ), instead of smooth , for purposes of locating the cap member 24 , hereinafter described , on the body member . the embodiment 10 , as mentioned includes a plastic cap member 24 , which can alternatively fit on either the ends 14 or 16 of the pen . the placement on or removal of the cap member 24 covers or exposes the writing mechanism 18 , as in conventional . the cap 24 may also be fitted with a pocket clip 26 . the illusion means or mechanism 30 has portions on both the body member 12 and cap member 24 . in more detail , the cap member 24 has an opening 32 formed in it , the opening being of a shape complimentary to the shape of the cap and of the illusion to be provided . illusion means 30 included a film element 34 and a background 36 which are secured in place to the cap member as by gluing or snap fit in an appropriate groove ( not shown ) formed about the margin of the opening 32 . the film 34 carries an image , in this instance that of an attractive nude woman ( indicated by member 24 ), which is otherwise transparent . the background 36 is opaque or non - transparent ( indicated by the numeral 38 ) except for portions thereof which are to be made to appear and disappear , in this instance the woman &# 39 ; s bathing suit ( indicated by the numeral 40 ). the portion that is to appear and disappear ( e . g . the bathing suit 40 ) is clear and / or translucent . the background &# 39 ; s opaque portions may be formed by directly painting onto the inner surface of the film . by painting it on the inner surface , the film serves as protection for the applied coating . otherwise , the background is placed behind the film . the body member 12 at its upper end 14 carries a different color , preferably black , area or portion 42 ( as indicated by the cross - hatching ) which can be made to align with the transparent area 40 of the background 36 , when the cap is installed in the body . the different color portion 42 does not extend completely around the entire circumference of the pen , but is of a size to cover only the clear area 40 of the background 36 . a convenient manner in which to form the different color area is to apply or paint it onto the body 12 , as by silk screening . in this instance , the opaque portion 38 of the background 36 can be a desired color , and the color of the pen member 12 ( other than for that of portion 42 ), is such as to permit the features of film 34 to be seen . as can be seen in fig2 when the cap member 24 is relatively positioned on the body member 12 so that the different color portion 42 is not behind the clear portion 40 , all the features of the film are visible , i . e ., the woman appears to be nude . as seen in fig3 simply rotating the body member 12 and cap member 24 relative to one another , as indicated by the arrow 39 , so that the different color portion 42 is behind the clear portions 40 changes the illusion . in such position the dominant dark different color area 42 is seen through the clear portions 40 and causes the features on the film 34 directly in front to be obliterated giving the appearance of the woman being clothed in a dark bathing suit . referring now to fig4 through 6 , a second embodiment 50 of novelty writing instrument of the present invention is shown . in embodiment 60 there is a body member 52 and cap member 54 . the cap member 54 is generally similar in construction to cap 24 of the first embodiment . as fig4 shows , the different color portion 56 ( indicated by the cross - hatching ) is formed by the entire upper end of the body member 52 . in embodiment 50 the change of the image or illusion occurs when the cap 54 is transferred from one end to the other end of the body member , instead of by relative rotation . as shown in fig5 when the cap 54 is over the different color portion 56 , the woman appears to be clothed in a bathing suit . when the cap is on the other end , as shown in fig6 she appears to be nude . while only the preferred embodiments on novelty writing instrument of the present invention has been illustrated and described , from the foregoing it should be understood that variations , modifications and equivalent structures thereof fall within the scope of the following claims :