The term 69 is common knowledge. It refers to male and female engaging in oral sex or spooning even in some books. But the term 89 refers to a man(9) either spooning or getting lost in a pair of big boobs (8)
To use a Texas Instruments TI-89 to pass a calculus exam, either easily or with difficulty, that would otherwise be impossible to do in the normal fashion.
I 89ed that test the whole way through, it was so easy then.