For folks that don't like being told what to do, they sure like telling people what to do HA
Playing with all the clients over time, I dig the Amethyst reaction emoji angle so you can just let someone know their joke hit or look at this, "ah" or whatever. Bringing pennies into that realm of mere reaction can ruin it I think. Leave the tips for things deserving a tip.
Its seeing a tip cup at a fast food joint type of lame maybe, I don't know but there should be a full spectrum available to communicate efficiently.