Leo DiCaprio had an interesting birthday party Saturday night ... in terms of what he fellow celebs chose to get him.
Robin Thicke may have slipped a present inside The Highlight Room in L.A., but probably more meaningful was that he took the mic and sang Happy Birthday,.
Director Alejandro González Iñárritu -- whose movie "The Revenant" won Leo an Oscar -- showed up humble.
There were lots of other stars ... Jamie Foxx and The Weeknd.