The number 9001 when read upside down. Can be related to the over 9000
meme, due to the fact that the first natural number above 9000 is logically 9001, and thus, if read upside down, can create humorous misunderstandings, due to the fact that the mistake is not as obvious as if someone were to read 9000 upside down (which would be read as 0006, making absolutely no sense for the placement of extra three zeroes, likely altering to the upside-down reading too early to be funny for anything).
(Goku just arrives on the scene)
Nappa: Vegeta, what does the scouter say about his power level?
Vegeta: It's 1006.
Nappa: What, really?
Vegeta: Yeah, kick his ass Nappa!
Nappa: YEEEEEEEEEEAAAAHH (charges into battle with Goku)
(Nappa getting beaten to pulp while Vegeta just stands there)
Vegeta: Huh, that doesn't seem right. Wait wait wait, Nappa.
(Nappa gets kicked over to him)
Nappa:WHAAAAAAAT!? (in pain)
Vegeta: I had the scouter upside down, it's over 9000. Rah. (says that while crushing scouter)