Hydrogen Bomb
"Hydrogen Bomb" is a very cool trick that was created by Bob Rule.

Like all tricks, there are many variations to it. I'll just teach you the version I learned. Let's first discuss this trick.

This trick is similar to the Atom Smasher. Knowing how to do the "AS" is a prerequisite. This trick involves a very awkward mount called the "Over/Under" mount. You have to throw a breakaway and then turn 90 degrees to the left immediately following that. If you don't do it properly you could get whacked in the arm or worst, the head. So be careful. You also do two under passes, both with your left hand and a couple of somersaults to finish it off.

Throw a super long breakaway across you body. It's sort of like doing a trapeze but you don't land the trapeze, instead you miss on the inside and let the yo-yo keep on going.

Now here's the tricky part. Immediately turn your body 90 degrees to the left. As you're doing that stick out your right index finger to intercept the string. Also lift your left hand up higher. You have to do this in one quick complete motion; breakaway, turn 90 degrees, stick out finger. From this point on the string and yo-yo will be directly in front of you perpendicular to your body, as if you were doing a Braintwister.

The yo-yo should hop over your right index finger and land on the string. It's almost like the Atom Smasher's 'split bottom entry' but somewhat backwards.

We are about to begin the first underpass with the string coming from the yo-yo finger of your right hand. To get to this position lift up the right hand (yo-yo hand) and bring down the left hand like shown.

Pull the string out and in a downward motion. This underpass is done with the index finger of the left hand.

Try to thread the string into the groove of the yo-yo.

The first underpass is complete.

Time for the second underpass. This is done with the newly coloured yellow string and with your left hand again. (Advice: Do the the 1st and 2nd underpass in one complete motion without stopping, like you're drawing two circles with your left index finger.)

Remember: Only thread in the white string.

After you complete the underpass you'll arrive this position.

Pull the right hand down at an angle.

This causes the yo-yo to make one rotation around the left index finger.

Time for backward somersaults. Do 1 or 2 or more if you want.

Do some somersaults. Again, do as many as you want.

Well that's it. I'd like to thank the guys on IRC (Shawn F. & Eric G.) for giving me a hand in describing this trick.

It was hard as hell to learn from a text description, so I hope you find it easier with the pictures. I had to learn the hard way.