The effect of the trick: 
Two cards, inserted into a deck at very different points, magically come together.

This trick is a simplified version of the card trick called Come Together.

How the Best Buddies card trick is done:

First, hand a pack of cards to an audience member and ask them to shuffle it and cut it into two fairly equal piles, giving one to you and keeping a hold on the other.

At this point, you sneak a peek at the bottom card of your pile. Our page about peeking at a card will help if you are a beginner at card magic.

Ask the volunteer to select a card from their stack, to secretly look at it, remember it and then place it on top of his pile. While the helper is doing this, you make a show of doing the same. However, unbeknown to the volunteer, you don’t actually remember your card, – it doesn’t matter at all – the important card for you to remember is the one on the bottom of your pile.