Brainfrozen

This is the fifth episode of Phineas And Ferb Forever, when Phineas And Ferb make a milkshake machine, Candace tries to bust them, but their Mom tries a milkshake and doesn't believe it's a problem.

Summary
Phineas and Ferb are making a new machine, Gretchen comes in. "So, what's that?" she asks, Phineas explains that it's their new Milkshake Maker, with Milkshakes in over 30 flavors. Gretchen tries vanilla and gets a Brainfreeze. She laughs and enjoys the milkshake.

Meanwhile, Perry is pounding on the stove, his lair entrance won't work, and the stove opens, almost crushing him. He jumps in and is teleported to the lair. Major Monogram is giving him a lecture on how Phin and Ferb's food is disappearing in the oven and that he should choose better lair entrances. Perry shrugs, and Major Monogram explains that Doof isn't doing anything today, Perry, annoyed, walks away.

Candace is trying to get Mom to go outside and bust Phineas and Ferb for their Milkshakes, for once, their Mom comes outside, seeing the machine, runs over and asks if it's an old Milkblast 2.0 from the 90's, Phineas said yes and that it was a modified edition, their Mom tried a blueberry milkshake and told Candace that she was crazy if she wanted her to bust them for this. Candace just sighs deeply and goes back in the house. Perry comes back and licks some dropped Milkshake on the ground.

Songs
Brainfreeze

Trivia
Their Mom sees their invention once more, and didn't bust them because it was a harmless machine, and it was a modified edition of one of her favorite Milkshake machines.