Leaving two pennies as a tip
Bad tipping is a subject that deserves (and gets) its own long-winded list of shitty practices, but this one deserves special mention. If the service is so bad you don’t feel it warrants a tip, whatever, fine (not fine, but let’s just move past that for the sake of argument). But if you leave two pennies instead of just leaving nothing, there is a special place in hell for you, you smug, sanctimonious wank-dolphin.
Failing at mixing credit and cash
So, splitting checks is fine. Yes, it’s an annoyance, but it’s a part of the job. You know what’s not fine? Saying you’ll pay for X amount on one card, X amount on another card, and “the remainder” in cash.
You probably don’t see the issue here, and I don’t blame you. In a just world, this actually wouldn’t be a problem; there’s nothing THEORETICALLY wrong with doing this. But what happens in practice, roughly 90% of the time, is the person with cash says “I’ll handle the tip,” the people who paid in credit don’t leave a tip, and the person with cash tips 20%... on the CASH amount they paid on the check.