Lock them in a room together and conveniently leave for a few days. The surviving on the incident may just bring them together; though they could eat each-other, but how much closer could two people get than that?
Lol! I DON'T anymore!! Anything bad that happens usually comes back to the ones who did the vouching for and introducing!! Or all you get is one of them or both of them constantly bugging you about the other!! So I guess...... be sure the person or persons you are vouching for to the other are worth vouching for and you trust them and Just be careful and be sure you want to involve yourself in such a venture!! It can get quite time consuming and bothersome!! and you could potentially lose a friend or 2 in the process!!! The best way to get them together if you choose to is just invite them both over to your house and play some games like cards and make some food and just hang out!!