How to tell if you are psychic
There is a silly Korean game that I play on M. to bamboozle him. It's the verbal equivalent of the card game Snap: whenever someone says the same thing as you at the same time, you have to say "Chi-chi-bon!" first. If you just sit there dumbstruck, you're going to get pinched. If you react in time by saying, "Mat-jang-gu!" then you are saved.
Every time I've played this on M., his reponse has been, "What?!" and indignant outrage at the fact that I pinched him. Now, that's not the way to play. You have to learn to say the right thing at the right time. Fortunately for M., the occasion triggering the game has happened only about three times. We haven't forged a scary twinning of emotions, it seems. But imagine what would happen if you were the sort of couple or pair of friends that are paired at some sort of subconscious level - you'd learn the game pretty fast.
Of course, it is probable that this so-called psychic link is merely a series of coincidences - if you spend a lot of time together with someone and if you are sensitive to what happens around you, your subconscious picks up on the subtle things. But it's fun nevertheless, and sometimes make-believe strengthens the gossamer veil of fact - by being more aware of what the other person is saying all the time, you end up knowing better what they'd say. That's my excuse for carrying on playing that game with M.