This is why I always try to pay for food or drinks as soon as possible.
Once in Brazil I walked away assuming my wingman had already picked up the tab. The misunderstanding was obvious and nothing happened.
I once walked away without paying at Swensen's (Big C in Pattaya). I must have acted and looked conspicuously absent-minded because they didn't even raise a fuss, just called me to my senses while I was drifting away at a very slow pace. Another time I'd taken a SongTaew to the Bangkok Bank branch after suddenly noticing I'd just left my debit card inside the ATM. I was in such a panic about the card I stepped away from the SongTaew without paying for the ride. Could have got nasty.
I am the dreamy, absent-minded type, especially when I have a lot on my mind, and as I go out to eat and drink every single day, the odd mishap is bound to happen sooner or later. Scary.