underage rookies

so i was watching sports center and smoking a joint and i got to thinking......what happens when an underage basketball or baseball player wins it all? are they allowed to celebrate with the rest of the team and pop the champaign? what if kevin durant and the sonics won the finals this year? he isnt 21 yet so does the team allow him to drink the champaign? miguel cabrera was only 19 when he won the world series with florida in 2003. do you guys think that the team kinda just turns their shoulder or do they strictly forbid them to drink?