A penny pincher is someone who takes money out of the communal meal payment (deposited on the table like a poker pot) because it represents more than 5% tip. In

A penny pincher is someone who takes money out of the communal meal payment (deposited on the table like a poker pot) because it represents more than 5% tip. In other words, they effectively reduce their own tip below 5% because someone else tipped a higher, more socially-acceptable percentage.