[gruseom]

The research in support of that suggestion is execrable (pun intended).

It's not really a pun. "Execrate" and "excrete" aren't related. (Sorry for the distraction; I find these things interesting.)

[_pius]

It is a homophonic pun.

The associated Wikipedia article is pretty fascinating: http://en.wikipedia.org/wiki/Pun

[gruseom]

Execrate and excrete are not homophones. But yes, that is a good Wikipedia article.