You Lost a Bet, or You're Being Pressured Into It
Getting a tattoo is a pretty big decision for most people, and shouldn't be the result of peer pressure. Don't make any bets that end with someone getting a tattoo, and don't let anyone pressure or force you into getting something you don't want. It's your body, your life, and you're the one that has to live with it and see it every day.
This goes for relationship and friendship tattoos, too. While most don't last, a tattoo definitely will, and anyone worth having in your life won't pressure you into getting a tattoo you're not comfortable with.