you've been friends with this dude named 'Gary' and you two hangout like how guys do

Until one day...

'gary' decided to show you 'his' secret

She unzips her jacket, revealing her busty voluptuous curvy female body... Her real name's is 'Gina' all this time

You've been hanging out with a girl...

Gina: "Hah! You idiot! I knew you always fall for my tricks~ hehe! And no, I've always been a girl, you stupid idiot! Hehe~ my idiot~"