I fart in the envelopes then they are like ‘yay someone wants our credit card OH NO ITS FARTS!’

When I was in college my roommates and I would open all those offers standing at the mailbox, seal the empty envelopes back up, then put then right back in the mailbox for the carrier to grab the next day (or maybe mail thieves, who knows). We figured just mailing them all back was going to cost something.