Follow these very serious and completely foolproof steps and no one will ever doubt you again.
First, whip out your credentials.
You should keep on your person at all times a definitive list of all the people you have ever been romantic with. This should properly suffice as proof of your sexuality.
Or, you can simply flash your official permit.
Every bisexual person is issued an official permit upon coming out, after of course providing the credentials mentioned above.
Is the individual confronting you still confused?
OK then, complete a physical test of endurance and stamina.
Bisexual individuals must be physically superior, or else we wouldn't have sufficient energy to be crushin' on so many people ALL AT THE SAME TIME.
