Well, When my almost 4 year old has a day care friend over, I just go buy some snacks (Usually healthy, but the kind that kids like!!)
And I would rent a movie for them both, like little bear is a favorite in my house!
When I would give them a room too play in across from mine, I would have there door open, and mine, and keep an eye on them 24/7!
And yea, I always enjoy it, so does my daughter.
(Honestly I didn't know if you were the parent of the child, so sorry if this doesn't help you at all!)
If your talking about having one yourself... err, just go with the flow? and have fun.