Short for "berries and cherries", meaning a combination or collection of blue and red lights, usually flashing. Can also be used when referring to police vehicles with the lights on.
Example: "Hey man, you better turn off at the next street. It's b's and c's galore up ahead! Must be a DUI checkpoint or a big accident."
"Dude, I'm thizzin' so hard. I'm about to rave out with my b's and c's! You down for a lightshow?"
Driver: "Yo bro, toss that blunt out the window!"
Passenger: "What? Why?"
Driver: "We got some b's and c's comin' up on us fast!"