SHFFLing

Short Hop, Fast Fall, L-Cancel (SHFFL): SHFFLing, pronounced shuffling, is the combination of the short hop, fast fall, and l-cancel. Basically they are used in the order that they are listed, although if already in the air the short hop is not needed. This technique is used to perform air attacks that you can recover from very quickly and thus go into another move without delay. Once you short hop you should use an aerial attack (A attacks only). Immediately after this attack you should fast fall into an l-cancel. The l-cancel will get rid of any lag that you character would have had giving you the ability to pull off fast combos.

Here is yet another video that I found to help you out.