It has been claimed sometimes that the possessive 's is a contraction for "his" - but I don't think any serious etymologst would accept that.

But the practice of using an apostrophe to indcate that one or more letters are missing is pretty common - but not on a letter by letter basis. So instead of writing "a**holes" or "a***holes" it would, I suppose, be "a'holes". I can't say I've ever seen it written that way, mind you.