Who remembers when Big Bird called the cops because Mr. Snuffleupagus was lost?
When Big Bird realizes he hasn't seen Mr. Snuffleupagus for a while, he thinks him to be lost. So, against the objections of 1 or 2 adults (who, as usual, insist that Snuffy is just imaginary anyway), Big Bird decides to call the police and file a missing persons report. After calling (from Mr. Hooper's store?), we hear sirens, followed by the appearance of an anything-Muppet police officer; he is wearing a hat, a jacket, and probably a badge; his voice and disposition are akin to that of Biff. Big Bird proceeds to describe Snuffy to the officer as he writes the information down in his little book: he is a big guy, with lots of hair, has a deep voice, and says "Oh dear" a lot. I think Mr. Hooper tried to object to the whole thing, but they more-or-less ignored him. Throughout this exchange, Big Bird called him "Mr. Dooper" in lieu of the usual "Looper" at least once, and the officer called him that once as well!
In the next street scene, the police officer is looking around for this Snuffy guy. He then spots David standing outside and talking to someone through the 123 tenement window; I distinctly remember someone, likely Susan, tossing David a set of keys from inside the window. The officer looks on, and says "Hey, he's a big guy." David might have Afro-picked his hair then, not sure. "Hmm, lots of hair." Although David has a higher-pitched voice, at that point he said something with under-the-breath emphasis. "Hmm, he has a deep voice." Then David called out "Oh dear," to someone, but in an inquiring manner unlike Snuffy's typical melancholy voice; I suspect this might have been to Maria, since they were something of an item in those days. But that was enough for the officer, as he had "found" David and grabs him. David is like, "Whaaa?", at which point he, Susan, and maybe another adult set the officer straight (incorrectly) about Snuffy's existence.