I've long given up trying to figure out the bill at restaurants for group dinners when cash and credit cards collide. There's always too much money or not enough and someone ends up with more change than someone else and it's just a mess.
Once, my debit card got mixed up with a friend of mine at a bar and she put $20 more on her tab than I did on mine. I explained the situation and how we'd have to go back to the bar so they could credit the right cards and then call the banks so they knew was what going on. My other friend spoke up, "Why doesn't she just pay you the difference?"
"Oh." I had not thought of that. "That works too."
The best example was when I was going on a trip a few years with a friend and I owed her $600 for the plane ticket. Most people in this situation would write their friend a check or send the money through PayPal if they didn't feel like looking for their checkbook.
I am not most people, so I took the money out of an ATM. It wouldn't have been so much a big deal if the ATM hadn't spat it out in 30 $20 bills instead of six Benjamins, like I thought it would.
If you ever want to feel very, very nervous, I suggest walking around carrying 30 $20 bills in three separate bank envelopes after sunset. It doesn't matter if you have them inside a pocket of your purse that you have stuffed under your arm while power walking to your destination, everyone will be staring at you because you'll be acting like such a paranoid freak.
Of course, my friend was like, "WTF? Why couldn't you write me a check?" and I was all, "I don't know! I'm weird! I didn't think of it!" but I'm sure you assumed as much.
Thank god life isn't a sitcom or someone would have thought there was some shady business going on and the madcaps that would have ensued from such a misunderstanding would leave even Jack, Chrissy and Janet with a headache.