Drill Bros.

Baby Drill is a technique used by Baby Mario and Baby Luigi in Mario & Luigi: Partners in Time. The babies learn this technique shortly after they receive their Hammers in the Vim Factory. It is taught to them by the L33t Hamm3r Broz., and allows the toddlers to burrow underground - avoiding enemies and allowing them to slip under the tightest spaces. The babies cannot dig through hard materials (such as metal), and will receive a Bean if they surface on an 'X' marked spot.

Trivia

 * In Mario & Luigi: Bowser's Inside Story, Mario and Luigi learn a similar drill move that performs the same and is also used to find beans.
 * When the babies use Baby Drill when the bros. are inside Yoob, at the upper screen, he is seen blowing smoke from his nose.