I remember on Family Guy, they made fun of Sesame Street characters a few times. One time, they were watching the Count on TV and Peter asked if there was ever an episode if the Count ever bit into someone's neck and sucked their blood. And Brian said, "No."
And another time, Stewie was making threats to Ernie on his SS talking phone. He said he already did away with Mr. Hooper.
And it showed Ernie and Bert sleeping in the same bed. Ernie wished Bert wouldn't drink and Bert wished that Ernie would stop eating cookies in the bed.
And when the family visited New York, Big Bird flew in for a cameo.