Or just get up and make a show of leaving. Hat and coat and all that. The server often snaps right into gear at that point.
But there have been two times I’ve walked out without paying. Both times it was the bartender I failed to pay.
The most recent time, all I had was a beer. I paid for it, but didn’t tip. The beer was $4.25 and I paid with a ten. The five I got back was then the only cash I had on me. When I finished my beer, I figured I’d have the bartender break it, and I’d leave him two. Could not get his attention. He was serving other people left and right, but totally ignoring me. He never said “be right with you” or anything like that. And I bet I stood there for a good ten minutes. After a while I realized I was wasting my time practicaly begging to give my own money away to someone who clearly didn’t want it. I walked out.
The other time, I ordered a salad at a bar. I’d been to this place enough times to know that the service was terrible, so I bypassed the whole waitstaff thing. The salad was something like $7.50. I had nothing but a twenty. When it came time to pay, once again I used my remarkable powers of invisibility. The girl would walk past me to serve someone else, and I’d wave the twenty right in her face. Too busy? Nope, when she was done she’d go back to watching TV. Once again, this was probably about 10 minutes of trying to pay her. I figured I could just leave the twenty and go, but no way in hell I’m tipping someone a 166% tip for absolutely no service at all. And I figured when she saw me leave, she’d chase me down.
Nope. She never did.