When Ted signs up with a matchmaking service, he learns that love is not a science. Marshall and Lily confront a creature living in the apartment.
This episode provides examples of:
- Cryptid Episode: Part cockroach, part mouse, capable of flight.
- Eek, a Mouse!!: Lily and Marshall named it a "Cockamouse", half mouse, half cockroach. They even fear that it might be a cockroach that ate a mouse and is using it's fur.
- Getting Crap Past the Radar: "Heh. Happy ending."
- He Who Must Not Be Seen: The "cockamouse" is never clearly seen.
- Heroic BSoD: Happens to the Matchmaker, after trying hard to find a woman for Ted, which was proved to be an almost impossible task.
- Hope Spot: Invoked by Ted on why he won't give up.Ted: I don't know, but I believe. Hell, if a cockroach and a mouse can find love in this crazy city, then, damn it, so can I.
- Hospital Hottie: Ted's "perfect match" is a doctor. And she's pretty.
- It Is Pronounced "Tro-PAY": Barney uses the alias "Jack Package", pronounced "Pakaj".
- The Matchmaker: Ted gets convinced to use this service of 100% rate of success. Turns out Ted didn't get a match.
- Oh, Crap!: The wonder Marshall, Lily and Robin have in seeing the "cockamouse" fly once tossed out the window quickly gives way to horror when Marshall realizes it's coming back to the window.
- Pest Episode: Lily and Marshall have a "cockamouse" in their apartment.
- Secondary Character Title: The title refers to Ellen The Matchmaker.
- Skeptic No Longer: Marshall and Lily (both a bit superstitious) are convinced their apartment is infested by a mutant combination of a cockroach and a mouse (which they dub a cockamouse). Robin plays the role of skeptic until the end when she finally sees the cockamouse herself (though we never do), and it's revealed that somehow the cockamouse can fly too.