to get the blood flowing to the penis without necessarily being in a sexual situation.
My doctor is a hot woman and I needed a testicle exam. Being it was a freezing cold day I needed to chub up before she came in the room.
to enlarge the penis without making it look erect, just to get the blood flowing. Making it look flacis, but slightly longer/thicker than normal
to unshrink the penis
he needed to chub up a bit before she came in the room, so as to loosen up his shrunk penis