MENLO PARK, Calif. — They may sport love handles and Ivy League degrees, but every two weeks some Silicon Valley techies turn into vicious street brawlers in a real-life, underground fight club.

Kicking, punching and swinging every household object imaginable — from frying pans and tennis rackets to pillowcases stuffed with soda cans — they beat each other mercilessly in a garage in this bedroom community south of San Francisco.

Then, bloodied and bruised, they limp back to their desks in the morning.

"When you get beat down enough, it becomes a very un-macho thing," said Shiyin Siou, 34, a Santa Clara software engineer and three-year veteran of the clandestine fights. "But I don't need this to prove I'm macho — I'm macho enough as it is."