Sesame Street Star Resigns After Second Underage Boy Accusation

The man -- who is now in his [20s] -- has filed a lawsuit against Clash ... claiming the two met on a gay phone chat line back in [2003] ... when the accuser was 15 years old and Clash was 32.

The accuser claims, "[Clash] trolled gay telephone chat line rooms to meet and have sex with underage boys."

In the lawsuit, filed in federal court in NYC, the accuser claims Clash "groomed [the accuser] to gain his trust by, among other things, taking him to nice dinners and giving him money."

The accuser claims while Clash was featured on "Sesame Street," he was "preying on teenage boys to satisfy his depraved sexual interests."

In the suit, the accuser claims ... although the sex occurred years ago, he didn't take action until now because ... he "did not become aware that he had suffered adverse psychological and emotional effects from Kevin Clash's sexual acts and conduct until 2012."