Mind the Giant! is the 23rd episode of Season 4. Marky accidentally eats some tree seeds which make him grow really, really fast, turning him into a giant roach who eats everything.
One night, outside Oggy's house, the trash can lid is opened by Joey and he was finding food. He took an apple core but doesn't have appetite and threw it back in the trash can. Dee Dee then ate it saying it is tasty. Marky on the other hand finding anything edible in the trash. He later found a tree seed packet. He took a seed and ate it, which he found it tasty and showed it to his brothers, but they are busy fighting over a bone. Without his brothers knowledge, he kept the seed packet and walked as if he did nothing. Later when the trio were sleeping, Marky took the seed packet and ate more seeds until he was full.
At the morning, the roaches woke up. Dee Dee and Joey were shocked to see Marky was slightly larger than usual. He managed by saying that he has grown up.