While Ashlee Simpson was showing off a picture of herself with Bronx Mowgli Wentz, daddy Pete Wentz was on Las Vegas one grind away from cheating with strippers.

On April 5th Pete partied with about 50 band members, dancers and pals, including Girls Next Door star Holly Madison, following a sold-out show at the Palms Casino Resort. A witness said:

"Everybody was going absolutely crazy. People were even drunkenly playing makeshift Slip ’n’ Slide with a mat and lubricant. Pete was in great spirits. He was dancing and singing along to his band’s own songs, grinding up against the dancers."

"At one point he was dancing on a pool table with the girls."

Earlier in the day, Ashlee, who headed back home after attending FOB’s April 4 concert in Irvine, California Tweated on Twitter: "I am beyond sad to leave my love… My heart is breaking as we drive home. I need my hubs."

Pete obviously wasn’t missing the Mrs.

Ashlee Simpson gave birth to a baby boy yesterday. His name is Bronx Mowgli Wentz (BMW). Pete Wentz is the dad. If anyone cares.