No need to wonder what Beverly Hills, 90210's Brian Austin Green did on his summer vacation. The fledgling musician showed off his new, dreadlocked look at a recent Fox party in New York City. ''I got bored, and it gets really hot during the day,'' says Green, who admits the hairdo may not go over well with 90210 honcho Aaron Spelling. ''Aaron hasn't seen [my hair] yet, so I don't know if I'll have it for the show,'' he says. ''But Jason [Priestley] and Jennie [Garth] liked it. Well, Jennie was laughing at first, but she likes it.''