Lindsay Lohan -- I Am NOT Doing 'Celebrity Big Brother'

Cameras follow Lindsay Lohan everywhere she goes, but she's not about to live with them ... telling friends she has no interest in doing "Celebrity Big Brother."

With LiLo arriving in London yesterday (see above), the rumor mill spun into overdrive ... saying Lindsay was in town to film the super-popular British show.

But according to our sources, the idea is "completely untrue" and total "nonsense." As one source pointed out ... how could she lock herself in a home for a few months when she has a court date next month?