Ray J -- Sued for Ditching Clothes in Whitney Houston's Death Room

When Whitney Houston died, a little bit of Ray J went with her -- well, Ray J's clothing anyway ... and now he's being sued for the expensive items that mysteriously disappeared from room 434 at the Beverly Hilton.

In recently filed legal docs, L.A. Stylist Marc Littlejohn claims he was hired to do Ray J's wardrobe styling on February 10 for a Grammy related event ... problem is, he alleges all the duds he let the singer borrow were left in Whitney Houston's room.

Houston died the next day in that room and, according to the lawsuit ... the pricey clothes haven't been seen since.

Now Littlejohn is suing Ray J for $2,880 -- the cost of the missing clothes -- insisting he's reached out to both the singer and his mother/manager repeatedly to get some cash or the threads.