Boyfriend to watch hot girlfriend with hot male

I am interested in finding someone who will make me feel relaxed, and to have a laugh with for a one time experience only...someone with a really toned muscly body (well endowed) as well as someone who is nice and decent person.
(Me and bf both like the idea, it is out of character and one off! Being discreet is also important).

If you are interested, it'd help to know what you like about this idea and how you would make it work....
(please don't contact if you're not interested in this idea)