“Sesame Street” is threatening a company for suggesting Bert and Ernie may have contracted STDs.

Mately, a company that makes at-home HIV/STD testing kits, used the BFFs in a new campaign aimed at sexual health awareness. Problem is, the ‘Street’ says nobody at Mately got an OK to use Bert and Ernie’s likeness.

A spokesperson for Sesame Workshop tells TMZ, “The Mately ad is an unauthorized, unlicensed use of our characters. We will be contacting Mately and the appropriate parties with a cease and desist letter instructing them to take this down.”

Mately got the message loud and clear — it’s removed all Bert and Ernie images from its site and says there was no intent to “tarnish the Sesame Street brand.”

Sex keeps getting the famous roommies in trouble. A few years ago “Sesame Street” had to squash rumors about Bert and Ernie being gay. The ‘Street’ clarified … they’re puppets and don’t have a sexual orientation.

This post was brought to you by the letters C and D (cease and desist).