Well, this certainly was quite the welcome.
Yes, this story really happened. Yes, it's been sitting in the back of my mind because I share it every now and then with people who complain about how nobody can count anymore.
The description of the "Side Bar" forum is "Because more things make us ask WTF than just code." Yes, I read the other change-counting threads. I didn't post to those threads because it wasn't in the same vein -- it wasn't the clerk asking "WTF did you give me all of this extra money?" It was me asking "WTF did you think I went out of my way to get $19.95 in change?"
MPS -- As to "What more did you want/expect from him?" Two things jumped immediately to mind:
* Tell my dad he must have miscounted, that clearly he was aiming for $20 in change but missed
* Assume the he (the clerk) miscounted, and give my dad $20 anyway
Anyway, I guess TRWTF is "WTF am I still doing here?" since clearly I'm not part of the good-ol-boys network.