Pi.
Pronounced p-i, like pi. Again? P-EYE. It's short for PIOUS, although in the goody-goody sense. When someone is altruistic, you say they're pi.

First appeared in Enid Blyton's Malory Towers.
A: So they say that Cancers are always thinking of how to make life easier for others...
B: Oh, bitch, please.
A: And they say Cancers always love everybody, no matter what.
B: What the fuck? Are they even human?
A: And Cancers' primary focus is on the fam and taking care of those they love.
B: PI, PI, PI.