The peer pressure badge is awarded if you get 3 downvotes on a question and you delete it. How are you supposed to get it, considering that you have a Reputation loss, just because of badge?
You get it just like it says, for deleting a post that has 3+ downvotes. It's one of those things most people don't actively seek, because it means you've intentionally made a bad post that the community doesn't like for whatever reason. So yes, it means you've lost at least 6 rep (2 for each downvote), but you have a badge. It's sort of a consolation prize, as it were (although you can only get it once, I believe.)