In the distant future, Numbuh 3's Granddaughter Sally Sanban defected to the Boys Next Door and brought with her a Girlifying Rifle so the Boys could reverse-engineer it to make a weapon capable of reversing the effects of Girlification. After the modifications, the rifle was tested on a Rainbow Monkey Doll and turned it into a football. Using materials found around their base (and probably broken/salvaged components from other Girlifying Rifles) the Boys were able to manufacture a substantial armory of boy-converting rifles for themselves. When Madam Margarets' mobile citadel arrived to destroy the last vestige of masculinity, the Boys were able to put up a decent fight against the Girl Squad only for Madam Margaret to activate her Girlifying Cannon which devastated the Boys along with disintegrating the Boys' modified Rifles in the process. However it was discovered that the assault against the citadel was a distraction for Numbuh 4 and Sally to infiltrate the fortress from below and access Margarets' time machine in order to change the past so Margaret's Girl-Dominated future would cease to exist. The old Numbuh 4 goes back in time to warn the Sector V of the past and Sally would subsequently destroy the time machine to insure that Madam Margaret can't follow Numbuh 4. With the help of the Sector V from the past, Numbuh 3 and Old Numbuh 4 are able to destroy Margaret's past time machine and save his past self. With the destruction of the time machines from the future and past, the Girlifying Rifles (and by extension the Girl Squad and Old Numbuh 4) faded into oblivion.
The beam fired from this weapon can instantly turn anything feminine, such as boys into girls, and grass into flowers. The beams also effect tomboys (girls with boyish personalities), turning them into girly girls, as seen with Numbuh 5. The beams however have no effect on anything and anyone that are already very girly as H.I.P.P.I.E.-H.O.P. and Numbuh 3 were completely unaffected by the beams.
It shows that boys hit by the laser don't mind the transformation and go on with their life as girly girls. It is the same with the reverse-engineered version as well.