Stick something long and hard inside me and see me get bigger until the job is done. What am I?

Latex gloves maybe, but thats not it

But very good answer that could work if you think about it

@HumanEarth No, I think that they're actually spandex type material, similar to leggings.

They're sold as "magic" gloves because they are supposed to be one size fits all.

Your not even going to quess

@HumanEarth

Your hole