Straight people - “That means you’re gay”

Gay people - “That means you’re straight”

No, they’re asexual.

Straight <=> being only attracted to people of “opposite” gender

Gay <=> being only attracted to people of same gender

{People of same gender as them} ∩ {People of “opposite”/different gender as them} = ∅

=> They are only attracted to the people in the empty set i.e. nobody.