Even though SpongeBob revealed the truth about Patrick, Marty and Janet still didn't believe Patrick was dumb (being dumb, themselves) and started laughing at SpongeBob, who ran out of the house in fury. When Janet and Marty reveal their names, Patrick gasps and demands to know who they are.
Befroe Patrick can do something, Squidward arrives with another starfish couple, who reveal themselves to be Patrick's real parents. Janet and Marty realize they don't have a son and leave.
Marty appears in "I'm With Stupid." Marty is married to Janet and comes to Patrick's house for Annual Starfish Day. He is Patrick's fake father. Like Janet, who resembles Marge Simpson, Marty looks like Homer Simpson. He has bushy eyebrows and wears a gray tank top, with blue shorts. He is a darker shade of pink than most other starfish in the series.
"Oh, right, we don't have a son."
"You taught him math too?!"
"And you taught him to sing!"
"He's short-circuiting! You must have taught him too much!"
"Son! You recognized us this time!"
"Wow, son! You put the drinks in something this time! Ah, son, you must've been working all night to put these together for us."