The ordering window is a smashed hole on the left side of the Krusty Krab's wall. Due to Mr. Krabs' cheapness, the drive-thru consists of a menu written on napkins, a microphone made with tin cans, and a sign made from a noodle.
"Driven to Tears"
As Patrick drops SpongeBob off at the Krusty Krab, Mr. Krabs informs SpongeBob that he is in charge of the drive-thru the restaurant recently installed. SpongeBob is in confusion upon hearing this, as he never realized the Krusty Krab had a drive-thru before, though Mr. Krabs tells him that the service was implemented as a result of many citizens on the go who don't have time for a sit-down meal.
After Mr. Krabs' attempt to fill a hole in the Krusty Krab's wall with toothpaste fail upon said toothpaste dripping and causing the hole to crack, Dave and his two children mistake it for a drive-thru and order from it. This gives Krabs an idea to install one to the restaurant.
Mr. Krabs makes the ordering window bigger by hammering it after SpongeBob fails to deliver a tray to Larry's SUB. The drive-thru eventually results in a fine from a policeman due to all the traffic Krabs has caused. He immediately demands a Krabby Patty. The mayor then visits and isn't satisfied about the cars holding up the drive-thru's line.
Mr. Krabs solves the problem by smashing a second ordering window in the restaurant, which interferes with SpongeBob and Squidward's ability to serve the customers in a quick enough period of time. As a result, the customers start rioting and Squidward is worried about what they'll do. Mr. Krabs resorts to smashing yet another hole in the restaurant, which destroys the building and dissolves it into debris. SpongeBob jokingly admits that this problem can be fixed if they have more toothpaste.
There is also a SpongeBob SquarePantsbook where the Krusty Krab installs a drive-thru. However, it was released in 2004, before "Drive Thru" or "Driven to Tears" even aired.
Unlike in "Drive Thru," the drive-thru in "Driven to Tears" has a real ordering window rather than a hole in the wall.