You pretty much will get ID'd unless you look a lot older than you are. I get ID'd all the time over there (then again I dont look my age) A couple of years ago the story was that the police are actually trying to shut down the coffee shops, so if they get caught with underage people in them they get shut down instantly, and never reopen - so theyre pretty uptight about ID. Either way you will have fun though, its impossible not to. Tip of the day: dont look at, talk to, respond in any way to anyone on the streets trying to get your attention. Totally blank them, the second you even look at them they'll latch on.. but you'll learn that pretty quickly