Rihanna -- Roof Creeper Ordered to Get Mental Help

Here's a good lesson: don't creep around Rihanna's roof ... or you'll find yourself in a buttload of trouble.

TMZ broke the story ... Rihanna obtained a restraining order against a man named Robert Melanson after he was captured skulking around her roof on June 17th.

In addition to being hit with a restraining order, Melanson was charged with criminal trespassing.

Now the buttload of trouble part -- Melanson pled no contest this week to the trespassing charge, and was subsequently sentenced to time served in jail (6 days), 3 years probation, $344 in fines, and one year of mental health treatment.