Lindsay Lohan -- Did Somebody Say COACHELLA!?!

Never one to let a little thing like an impending trip to rehab get in her way, Lindsay Lohan descended upon Indio, CA last night with her brother to hit up the Coachella Valley Music and Arts Festival.

As TMZ first reported, LiLo has been swearing to friends that despite the numerous temptations Coachella brings ... she plans to stay completely clean throughout the weekend.