Mr. Monk and the Secret Santa - S4-E9
Corrected entry: The title of the episode does not match the plot, since in the show the gifts are not given secretly. As the name suggests "secret Santa" is when the identity of the person giving the gift is secret. In the episode, the names are drawn out of a hat and are then handed by the person giving the gift to the recipient. The identity of the giver is not secret. More correct would be "randomly allocated Santa".
Correction: The gift exchange itself was not a secret, but the murderer sent the bottle of port to Stottlemeyer under a fake business name. The murderer was the Secret Santa.
SJActress