From the Super Mario Wiki
Eekers are monsters fought in Mario & Luigi: Superstar Saga. They are found in Woohoo Hooniversity, but never on the field, instead showing up alongside Viruses. The Eeker has two attacks. Its first attack can be spotted if the Eeker runs up to its target and starts filling up with fire. Mario or Luigi must use their Hammers to defend before it fills up, or it will shoot deadly fireballs in all directions. In its second, more common attack, it will cross its arms one to three times and tilt an equal number of times before lunging at its target. Jump to counter after the appropriate number of tilts.
Eeker is a portmanteau of "eek" and "beaker", though the creature more resembles a flask than a beaker.
Names in other Languages
||Pun on "Frasco" (beaker) and "Bailarín" (dancer)
||Possibly variation of the English name