When you put a thought in the back of your mind and intent to get back to it later only to forget what is was. Happens when you have too much to worry about right now.
Stan: "Did you complete your assignment for Monday?"

ME: "Oh SHIT !!! I completely forgot, with all the preparations for Sharon's birthday this week. I guess it fell off the back of my mind !!!
by sarafi March 13, 2011
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Twitter Dude: My Grandma just died
Random Guy On Twitter: Ratio+You Fell Off+ YB Better
by Adifiddid October 29, 2021
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A term used to describe something that you haven't heard or seen in forever.
Me: Dude, is that a Yugo?

Friend: Dafuq? I haven't seen one since i fell off my dinosaur
by batmanbinsuparman June 14, 2012
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A sarcastic reply, used when you don't understand what the other person is saying (commonly technical).
Frenchie: C'est ville quos muos pume rouge j'aime marsh'mallo
Paul: I had one but the wheels fell off.

or

Person A: All you have to do is remove the hydraulic overhead slip ring so the cam will meet the side flange.
Person B: Yeah, I had one but the wheels fell off.
by weavile22 December 27, 2011
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A term originating in Montgomery and Bucks County. It's largely seen as a derogatory word towards women. It's used to call a specific women a useless slut.
Jill: Hey Billy I am so sick of you, you are such an asshole.

Billy: Wow Jill all I know is I remember when I fell off my dinosaur and I am glad we are through.
Jill: You are such an asshole.
by 1258DRag April 24, 2015
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Another way for a female to say she is menstruating.
Girl #1: Are ya' going to the lake today?
Girl #2: Naw, I can't. Granny fell off the roof and has her arm in a sling.
Girl #1: Aw, that's too bad. I'll catch ya' later.
by goobershanker April 6, 2004
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