Drink.<p>Alcohol (and possibly other recreational drugs) binds and cements friendships. After a few drinks, people are more open to talking about themselves in a more honest way and tend to reveal more of the person that they really are, rather than the person they present to the world in normal, sober life; as the old phrase &#x27;In vino veritas&#x27; attests.<p>Note that I&#x27;m not advocating or encouraging alcoholism here; I&#x27;m talking about two or three sessions a week with a select few people that you want to foster a deeper relationship with. Also, friendships (as opposed to drinking buddies) are based on more than just alcohol. Friendships are ultimately about trust.