Britney Spears used one of the oldest tricks in the book in an attempt to get out of a recent traffic stop, explaining she had to go to the bathroom ... which caused her to cross the double-yellow traffic lines.

We've obtained the body cam footage from the California Highway Patrol officers pulling Britney over on two separate occasions -- September 10 and October 6 -- near her home in Thousand Oaks.

During both exchanges, Britney is super apologetic and explains she's just coming back from a vacation. However, during the October 6 stop, she blames having to use the bathroom for passing on double yellow lines, exclaiming, "I'm so sorry, I have to use the bathroom ... it's about to come out right now. I'm so sorry."

During the September 10 stop, Britney's pulled over for going 61 mph in a 40 mph zone. Again, she's apologetic, but also gets busted for driving without her license and proof of insurance in the car.

We should note, Britney explains her security usually holds onto her documentation ... but that's not enough for the officer, who lets her know she's gotta keep it on her at all times.