It's simple. Snap a pic of your ugly mug or upload one, put a funny caption on it and wear your SelfieTee to that upcoming party, or that trendy hipster festival, or to class, or wherever you want because America.
Do you actually have friends? Make a SelfieTee for your best friend with both of your faces and a cute caption like "#BestBaes4Eva" - you know, something to make the other baes jealous.
Don't have friends? Have a pet? Put your dumb pet on a SelfieTee. Show everyone how lonely you really are.
Embarrass the birthday boy or girl with an embarrassing SelfieTee and get one for everyone at the party.
Take the bachelor and bachelorette party up a notch and get matching SelfieTees of the bride or groom doing something crazy while you crash drunkenly from bar to bar shouting "SUSIES GETTING MARRIED WOOOOOO!!!"
There are just too many options. Stop reading and go make one. They're cheap quick and freakin awesome.