Shockwave Attack - New Super Mario Bros
Most of you might already know this, but I didn't and neither did my brother so I thought I'd post it anyway.
You need at least 2 people to do this.
Start a level.
Get both players to ground pound at the EXACT same time.
If done correctly, it will cause a shockwave and a ping sound that will kill all enemies on the screen that are on the gound.
Added by: JakandDaxter3 Dec 19th 2010, ID#4187