In the Lair, there was a mutant flu going around. Mikey got it first, Leo took care of him while Donnie worked on a cure. Raph was helping Leo out. Mikey took advantage of him being sick and being the youngest sibling. He complained about everything.

Donnie made a solution that helped Mikey feel better, it was obly temporary though.

Donnie: “Mikey, take the damn medicine.” Trying to feed Mikey a spoonful of medicine.

Mikey: “Nooo, it tastes bad!”