I wonder if there's someone-

[heslopian]

I wonder if there’s someone
Everybody wants to fuck.

A charmer of nuns A charmer of nuns? Did you mean "chamber"?
And housewives
Who never had
To purchase cologne,
Slip anything
In a drink,
Or rely on a fifty
To buy company.

“Oh, that Gregory”
His mother would say. This confused me a bit. The focus went from a load of women to one specific man very suddenly, without much explanatory transition. Perhaps you could add another verse to ease Gregory into the narrative more?
“He’s been fucking
Since he knew
How to tie a shoe”
And of course,
The mother would’ve
Fucked him too. This made me laugh in a scandalised way

He’d hobble
To assisted living
And blood would roar
Through Grandmother’s legs An apostrophe isn't needed after "grandmothers," as it's intended as a plural here. Also, why is it capitalised?
Like a flash-flood; sprinting I think you need a comma after "legs" and "flood," putting "Like a flash-flood" in parenthesis. The syntax here is somewhat odd.
For the first time in decades

A very amusing poem, somewhat like a limerick. Thanks for the read