To me, hack is a word for a modification you could make that 1) takes only a short time to master/implement, and 2) shows immediate desired results
Thus, learning to play guitar is not a hack, since it satisfies neither criteria, but learning to put some TP into the toilet first when you do #2 in order to prevent splashback is a hack.
Thus, learning to play guitar is not a hack, since it satisfies neither criteria, but learning to put some TP into the toilet first when you do #2 in order to prevent splashback is a hack.