Allz I can really say, without getting into a rather disturbing story, is that indeed rubbing alcohol will kill roaches practically instantly, when drowned in it anyways.
Only warning I’d tack onto that is that if you happen to already have a hole in your eardrum, then rubbing alcohol probably isn’t going to feel too good. But then again, neither is a roach burrowing into your head, so choose your battles wisely.
For real though, as long as your eardrum is still intact and doesn’t happen to have a hole for whatever reason, rubbing alcohol in the ear doesn’t hurt a bit and will kill a roach in a matter of like 3 seconds or less.
Wise choice though, I wouldn’t want to sleep in a roach infested place either. Have you read through the rest of the comments for my Life Pro Tip on how to get rid of the demons cheaply and without poison?