What do you get when you cross a mosquito and a spider?
Nothing! You can’t cross a vector and a scalar!
(This felt appropriate.)
*Explanation after the read more
In biology a vector is considered an insect or other organism that transmits pathogenic viruses, bacteria, fungi, and parasites. A scalar, like a spider, scales things.
In math a vector is a quantity with both direction and magnitude while a scalar is a quantity with only magnitude. Thus, they are unable to cross.