Surfer On Acid tail?

I saw a video on youtube where a guy was making a Surfer On Acid and said that this is a drink that will get you in trouble with the cops and I was wondering why? I mean it looks harmless enough and obviously if you drink too much you will get drunk and possibly end up talking with the cops but he made even one rocks cup full sound pretty potent. It's only Jager, coconut rum and some pinapple juice, how bad can it be?