A man walks into a bar. He asks the bartender 'I've had a rough day, can I have a beer and a shot for every ex that I have?' The bartender pours him 12 shots. Why is that?"

The man's request for a beer and a shot for every ex implies that he has had a significant number of ex-partners. By serving him 12 shots, the bartender is suggesting that the man has had a total of 12 exes.