The YesDear 5000, or Boyfriend Helmet, is a helmet Lizzie used to get Nigie to spend time with her in Operation: L.I.Z.Z.I.E., instead of the KND. In Operation: S.N.O.W.I.N.G., Jimmy Nixon McGarfield modified it so that it would work on girls and make Lizzie his "bride". If the helmet is on the head of a mind-controlled person too long, it fuses to the victim and the victim is permanently under the spell. The YesDear 5000 works by controlling the mind of a boy (or a girl, because Jimmy was able to modify it) to act in a way desirable to the person's girlfriend (or boyfriend).