Pehraps a little rewording is required.
Flexing for anyone anytime is not "gay", last time I saw my gay friends walking around flexing was well ... never.
Is it however Chaci? or perhaps sad is a better term.
Then again it depends on your personality, I have a friend Titus that has a permanent ear to ear smile and he will do things like that out of the blue, and make comments like "Hey have you ever seen a more spectacular specimen?". All you can do is laugh, you know he isn't serious and it's just who he is.
Like mreik said, if people ask to see them cause they notice, hey show em off.
If you want to flex at home or for your gf, do it.
However if you find yourself posing into a double front bi as you go down to tie your shoe... you may need to release the valve on the side of your large melon.
Flexing isn't Cachi in itself, only people are.