Unconventional loans system

I have just had an email from a different area of our business asking if they can borrow something very important, expensive and delicate, without their really understanding how we use that item (It's in a working collection used on site), and why I can't just decide to loan it off site for the day (because I would be loaning out an item essentially already on loan to us... because it sets a precedent... because of loss/damage/handling...). 

They would be very grateful, and would "definitely arrange for some beer tokens to come your way in return"

This could be counted as offering a bribe/influencing in a rather bad way, were it reported in those terms. 
I have never been vaguely bribed before.
And that is a pretty sucky bribe.