How do I figure out if a friend of mine is gay, and if he likes me or not?

This will sound like decadent, but I recently discovered that alcohol is a veritaserum. Drink a fair amount of alcohol, like two gles or so, and make a jolly atmosphere with giggles or jokes, then if I understood correctly, he will reach for you. And then ask: "Do you like me?". He will hesitate probably, but then you say, "It's ok, I would like to know". You will get an answer. If he's been lying, you will notice a change in his mood, he will become kind of quick-tempered. I have used this method twice, one for a guy I liked and one for a guy that I thought that liked me. But nothing happened in either time, the first guy was straight and the other was gay, but it was just his attitude. But the method is just great.