Alli and the Ambulance Arrive at Brit's

1/31/2008 6:29 AM PST
Alli Sims was all smiles when she arrived at the chaotic scene surrounding Britney's home -- and had to cover her mouth to block her cheek-splitting grin!

The ambulance showed up shortly after -- led by a team of motorcycle cops to assist in Britney's transport to the UCLA Medical Center.