I had a coworker who did something similar out of spite. I don't remember why he owed the camp we worked for five dollars but he paid in back in pennies which he counted by hand. I said. "You know, it will take you much more time to get the pennies than it will take your rival to deposit the pennies."
In the UK, there seem to be very regular machine placements to automatically count your pennies and turn them into larger currency. Plus most banks have an automated deposit machine where you can just pour in the coins and it will count them for you. I imagine that America (being much more customer oriented than the UK) has similar things. So... not much of a revenge... and I for one kind of like holding a bunch of coins (or at least I did before the pandemic. I'm not a germophobe, but I'll stick to bank card now thanks)