It is not listed in the OED or any other major on-line dictionary.
Searching through google books, one finds this entry:
Trolloping part. adj. Walking through dirt and mire, as a slattern does; trudging. Sometimes 'Trollopsing'.
This is an entry in A Warwickshire Word-book: Comprising Obsolescent and Dialect Words, Colloquialisms, etc. Gathered from ...
Typically "loans" are used to describe the lending of money. You can say "loaned items" to be more specific or consider using "checked-out items."
A few other points: "Users" can be omitted since when you say "Those" it is implied, and "return in items" can be shortened to either "return items" or "turn in items".
A correct version would look like this:
Generally, when you ask a wh-question (that is, a question beginning with "who," "what," "when," "where," "why," or "how"), you must use subject–auxiliary inversion. By "must," I mean that your question will sound very strange if you don't.
There are are a couple of exceptions:
If the question word is (or is part of) the subject of the sentence, it remains ...
As pointed out by Edwin, this is a form of English known as African American Vernacular English. That's not to say it is wrong, but that it can only be informally used.
The meaning is there, but the sentence "Why you're laughing" is equivalent to "Why you are laughing", which is wrong, formally speaking.