Random Round Robin Partner assignment

[dvrcthewrld]

I have a set of user/member information, and each is given a unique ID at time of registration, and each user has a field for partner_id.  Registration is only open for a certain period of time.  At the end of that time, I want to run a code that will randomly assign "partners."  I want a round-robin sort of situation.  So, if I have the following 5 unique IDs: 4, 9, 15, 32, and 38, than the code might assign 9 to 4, 15 to 9, 32 to 15, 38 to 32, and 4 to 38.  Obviously that ordering isn't random, but you get my meaning of "round robin."

 

How on earth do I get that random round robin assignment that I'm looking for?  I haven't found anything in a week of searching.

 

Thanks.