[cptskippy]

We measure trunk space in terms of bodies it can hold. It's funny and clearly relates the capacity.

[CRConrad]

We do? Depends on who "we" is, I suppose...

I've seen golf bags mentioned quite often. But, come to think of it, that's about equivalent to a body, isn't it?

[cptskippy]

It's a common joke unit of measure to estimate the size of a small enclosed space.

An example: https://youtu.be/J-falgJE1xg?t=211