"Lost in the Supermarket" is the fourth episode in Season 1 of Clarence.
During a trip to the supermarket, Clarence finds adventure and intrigue in the aisles.
The episode starts out as Clarence waits outside of the school for Mary to pull up in her car. When she arrives, he informs her that Jeff has invited him to come to his house after school. Mary agrees to drop Clarence off at Jeff's house, but first, she has to go grocery shopping. Clarence then speaks to her about how much he detests going to the store and finds it boring. Mary talks him into going and Clarence gives in. As they come into the supermarket, Clarence runs into an obese lady on a motorized shopping cart thinking it's a go-kart. His mom then tells him it's rude and they walk the other direction. The first item they grab are organic grapes, and while watching the cart, Clarence sneaks a grape from the bag. A little girl behind Clarence sees him do this and tries to get him in trouble for "stealing" a grape. Mary tells the girl that she will turn Clarence in to police. Afterwards, the girl, with a smirk on her face, laughs at him. He is then sent on a "special mission" by his mom to find some skim milk. The milk he needs appears to be in the very back on the top shelf and he has to climb up to get it. Behind the shelf he finds the supply room and plays around in it by swatting a fly swatter, slipping on a banana peel, and just looking around until he is startled by a worker. He hides on a conveyor belt which starts to move Clarence onto the meat aisle. Clarence is then picked up by an old lady thinking he is steak, pinched and kneaded, and eventually placed in her cart. He is then carried in her cart and sees Sumo. Sumo asks if the old lady is his Grandma and Clarence tells him what had happened.
Noticing Sumo is seated in the cart Clarence questions why he is in the kids seat, and Sumo explains his mother makes him after, "What happened last time". When asked what happened Sumo merely gestures to a nearby worker, Joshua Maverick, who stands out because of a scar on his face. When Joshua sees Sumo, he glares, stroking the scar, implying that whatever happened last time caused the injury. Clarence then gets out of the cart and starts messing around with Sumo. The cashier Josh is then sent to clean up their messes. Sumo and Clarence run into Clarence's mom and her coupons go flying everywhere, and almost immediately fellow female patrons notice and pick up the coupons for themselves. Mary becomes saddened. Sorry for making his mom lose her coupons, Clarence gives her the skim milk, but without her coupons Mary has no choice but to begin putting her items back on the shelves. Clarence then decides to get more for her with the help of Sumo who gets caught by Joshua. While he also gets a paper from a cart, he runs into the same girl from before, who once again, tries to get him in trouble. He pretends to throw a smoke bomb and leaves with it. Clarence gives Mary the coupons and the manager stops Joshua from getting Sumo when he notices Joshua chasing Sumo. He does not seem to notice how roughed up Joshua is and the fact that Joshua is now missing a chunk of hair. Then as Mary goes to the cashier her initial cost is $280.00, though after using the coupons, the price becomes only $10.00. Clarence gets in the car and explains what happened at the market and Mary soon drops him off at Jeff's house where they watch a parody of "The Price Is Right." Finally, Jeff turns off the program when Clarence guessed the price of the item correctly and Jeff got it wrong.