I know. 
That was their first hit song, which probably explains why they couldn’t say v’s right in it.
Valete,
Vox Imperatoris
I guess it depends on what chart you’re talking about. I think if you checked out the country charts from the Fifties you’d find quite a few doozies. But sticking with the pop charts, I defy anyone to come up with something comparable to the following. On New Years’ Day 1972, a composition entitled “Once You Understand”, by a group known as Think, entered the Billboard charts. It stayed there for a majestic five weeks, peaking at #23. The “song” (I’m not sure that’s the correct term) starts with a chorus singing the line, “Things get a little easier/Once you understand”, over and over. This dissolves into what can only, for want of a better phrase, be called an extremely melodramatic theatrical sketch, in which a teenager fights with his parents and takes off, followed by the police showing up at the parents’ door with the news that their son has died of an overdose. The sketch ends with the parents’ hysterical weeping, as the “once you understand” chorus swells up again to close out the piece. I know of no other charted song that can hold a candle to “Once You Understand” for the level of sheer, mind-numbing, gut-wrenching agony it produces. Seriously, the interrogators at Guantanamo didn’t need to bother with waterboarding… just play this six or seven times and the most hardened Al Qaeda operative would have cracked like a DDT-laced eagle egg.
(And for those of you who really like this song … and I know there are some of you out there … I hope you’ll forgive me. Maybe we could agree on Bloodrock’s “D.O.A.”)
Ok, the key words in the OP are “hilariously” and “commercial success”. I think a lot of posters are forgetting that second one.
I submit Disco Duck.
It was a Billboard #1 for a week, and was in the top ten for ten weeks.
And a live version is even funnier.
Damn, now I’ve got that thing going around in my head…