People who borrow cash from me to buy something really small, like some drink that costs $4. I then see that they have a credit and a debit card in their purse and I ask why they don't just use that. They laugh and say, "Pshh, I don't want to put $4 on my credit card." I say, "Why not?", waiting for a logical reason... and they just kind of mumble something incoherent, then change the subject very rapidly to avoid more questions of the same nature.

I hate that so much, I seriously am in a bad mood now.