Wrong-o, Mary Lou - origin?

I’ve used this phrase at least since middle school (ca. 1975), but cannot remember where I picked it up from. Google-ing got me nowhere.

Any clues?

Dunno about the “Mary Lou” bit, but there was once a 7Up commercial featuring a rather stoned reindeer who said something like “Oh, I bet you think I’m just cooling my hoofies? Wrong-o! I’m an UnDeer! And… [something eventually about the refreshing nature of 7Up]”

Wanna bump this one up. I KNOW the answer is out there.

Perhaps from the song “Hello Mary Lou?”

Haj

I seem to recall it from a childhood commecial (early/mid 70s) but I can’t recall for what product.

It was from a commercial in the mid 70s featuring that lovable Tony the Tiger. (What was he schlepping? Frosted Flakes?)

I don’t remember what the deluded Ms. Mary Lou said to warrant such a rebuke from Tony, but after he said it, they all went outside to ride bikes, so I think she forgave him.

I can’t believe I was the first to actually answer a question.

Yay me.