OLYMPICS ice star Johnny Weir hit the dance floor, grinding with both boys and girls, to celebrate his 26th birthday. Witnesses said the three-time US National Men’s figure skating champ, and star of Sundance Channel series “Be Good Johnny Weir,” partied up a storm the other night at Hudson Terrace with pals including designer Richie Rich and his show co- star and best friend Paris Childers. (Weir likens their relationship to that of “a mar ried couple without the sex.”) Weir is working on his first sin gle, “Dirty Love,” and a clothing line, which he has said he wants to be “Chanel quality.”