Suggest a different penalty.

"Nah man, sorry" you say. Dave grumbles, "well, probably just as well, you were losing" he says, inaccurately.

"Is that right?" you say "Well then, how about we turn up the heat? Every time you die, you have to take off one item of clothing" you suggest.

"You serious?" he asks. Just now he's drunk enough to be suggestive, but it'd be best not to overdo things.

"Yeah, I mean, unless you think you'll lose" you challenge.

"You're on!" rallies Dave.

You begin playing again. The challenge seems to have sobered Dave up a little and he's making fewer mistakes. Maybe he was dying before to get more of the vodka? Still, his reactions are still pretty numbed. You could beat him if you wanted to, but maybe it would be better to lose the challenge?