"Is this supposed to be Rap?" Well, indeed
the Beasty Boys were some kind of pioneers in the 80ies with a fusion of Rap and Metal, long before the New Metal scence evolved with bands like Korn, Linkin Park, etc.
It's not my favorite stuff either, but I found it quite funny and interesting back in the days. Please try "Fight for your right to party", that's a real fun party song (if you don't know it already:-))