Randall the Cloud is a nickname for the Lakitu's Cloud that appears on Yoshi's Story in Super Smash Bros. Melee. It is often used to assist the recovery process. The term derived originally from Canadian smasher FastFox, and it has since taken off as a norm on Smash World Forums.
Randall's complete round trip through the stage and out the other side takes exactly 20 seconds. As such, many players attempt to "summon" Randall (via a strained shout) when falling. It is not uncommon that a player will fall just short of the edge, only to see Randall's smile as he emerges half a second later.
Randall does not appear for the opening ten seconds of a given battle and emerges on the right-hand side of Yoshi's Story immediately thereafter, meaning that the position of the cloud is consistent and predictable, not random. Through paying particular attention to the countdown in a timed match, a prudent smasher can use this knowledge to effectively stall a recover and land on Randall instead of taking a fall.