Start your engines!
Sources tell E! News that Britney Spears threw her boys, Sean Preston and Jayden James, a joint truck-themed birthday party on Saturday. Sister Jamie Lynn and her 2-month-old daughter, Maddie, were in attendance along with approximately 50 other guests.
Saturday was Jayden's actual 2nd birthday; Sean Preston turns 3 on Sunday.
The birthday boys and their little friends drove around in mini toy cars with personalized license plates. Britney was dressed casually in jeans and a green top, and was spotted watching the kids enjoying their new rides.
The party started at 2 p.m. at the Beverly Hills home of Dr. 90210 plastic surgeon Paul Nassif and Adrienne Maloof, sister of Brit's good friends Phil and George Maloof, owners of the Palms Casino. The mansion is situated in the gated community of Beverly Park.
*Additional reporting by Jeanifer Hwang