SKYDIVING. BUNGEE-JUMPING. WALKING on hot coals. These are challenges, but they pale in comparison with sitting through the current incarnation of Saturday Night Live. The show has been in a rut for a couple of years, but this season's early installments have been exceptionally bad. Most skits just sit there ticking like a time bomb, whether it's another lame O.J. Simpson trial satire, where the sole joke is watching Tim Meadows (as Simpson) grimace, or an inexplicable bit about a public access body-piercing show. SNL still has talented cast members. Too bad that at best, the writers go for cheap laughs, such as a labored segment featuring John Travolta as a vampire, and figure that the mere presence of a character such as the "Coffee Talk" lady or an O.J. reference will be funny. They're not. SNL now stands for Saturday Night Life Support.