The amount of money it takes to keep the other girl from telling your significant other about all of your outside sexually related activities.
John: Do you want to go to the bar tonight and catch the game?
Coach P: I wish I could, but I just dropped 100 in "hush money" on my sexretary for the second time this month. (see sexretary)
money paid to someone to buy their silence, to prevent them from revealing or making public something secret one does not wish to come out;
or just putting it straight and plain: money paid to someone for keeping their mouth shut, a bribe for somebody's silence.
She's been given enough hush money to keep her mouth shut till the end of the world and even a day longer, at least that's what she said. But you know women and alcohol - a dangerous combination of the two: at Peter's party last week she had had a drink or two too much and she let the cat out of the bag.