I don't think I'd have the gall to attempt these types of bets. It's kind of like losing a bet for $1000 and then trying to pay up with a Barbie's head. "I didn't say dollars; I said doll hairs!" LOL.
Basically, you could try to do that any time someone says, play for 50 or play for 100. After you lose, you can say, "well we never established 50 of what, so here's a million water molecules... keep the change!"
Trying to pull that off could be hazardous to one's health, I would think. The argument is that "play for 50" implies "play for 50 dollars"; "all the balls" implies "all the object balls".
Anyway, even with the strict wording, I think I have a way to turn the tables on this one.... After agreeing that you can make all the balls that are on the table without scratching, grab a cueball* off another table and run out the 7 original balls.
*Edit: I guess you don't even need another ball set. You can just grab an unused object ball from the same ball set and use that as the cueball (8th ball).
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Solution to the one from PoolHall Junkies... when the beer glass is over your shot glass, pull your shirt sleeve down or grab a napkin and use it to remove the beer glass. Say, "I didn't touch your glass; my shirt/napkin did."