To flashout is to get highly upset with another person (this may lead to an altercation). Most commonly when you flashout on someone it is on a person that you detest.
girl A:(dancing in the club and bumps into girl B)
girl B: Bitch you better watch where you going!
girl A: No you watch where you going!
girl B: Mane, im finna flashout on this hoe!
girl B: Bitch you better watch where you going!
girl A: No you watch where you going!
girl B: Mane, im finna flashout on this hoe!
by young thugs December 24, 2009