Our cameras caught Britney Spears leaving a Beverly Hills medical facility yesterday afternoon, when she received an unexpected gift -- a lawsuit!

As TMZ first reported, Britney Spears is being sued by a former manager seeking commissions he claims she owes him. The process server slapped Brit with the papers as she was entering her white Mercedes -- by tossing them into her passenger seat. Hey, looky there, them's officialated papers!

Brit had no reaction to the papers and pulled away listening to the old Madonna track, "Like a Prayer." Life is a mystery, indeed.