Working the drive-thru isn't as simple as you might believe. For one: Customer service can be grueling. Secondly: Customers are wild, man, which only supports our previous point.
Redditor MoistMania got the ball rolling after they asked the online community: "Drive thru workers of Reddit, what's the weirdest thing you've seen in someone's car?"

"A lizard..."
A lizard chilling on someone's dashboard being fed veggies. A cat was also in the same car.
"When I worked..."
When I worked at Dunkin' Donuts this guy came through the drive thru with a huge falcon in his passenger seat.
"A baby kangaroo."
A baby kangaroo. To clarify, I live in New England and this is not normal. To be honest I was just out of view of it, but it caused quite a clamor.
"Some guy..."
Working drive through at Starbucks...
Some guy pulled through with car filled with boxes. He said they were filled with flashlights and offered me some. I completely forgot about it till I got off work. When I got out to my car there were 5 boxes each filled with 20 brand new Duracell flashlights still in the packaging. Had to be worth at least $500. And he had many more boxes.
"A woman came through..."
A woman came through with no passenger side seat. It had been pulled out, and in its place hung a giant metal ring with an enormous Cockatoo sitting on it. Thing was going mental when she pulled up.
"My mother..."
My mother used to work the drive thru at Burger King when she was a teenager. She told me that a man used to come through some nights completely naked except for black see-through stockings.
"I was staring at her..."
Back when I worked drive through at a McDonald's I had this guy ordering who, number one, took like five minutes to order a breakfast burrito and a drink so I was pretty fed up already when he got to the window. When this car pulled up, I was really not expecting to see a chick wearing nothing but a bra and panties in the backseat.
I was staring at her while I took the guy's cash and she glanced up and noticed me and ducked down a little bit. Like, babe, you're in a pretty short car; if I can see the floor from here I can definitely see you.
Guy just drove off to the next window like nothing happened.
Also served a lady on a horse one time and was subsequently told they had to be in a motor vehicle to come through the drive through, but that wasn't as strange since there are horses in our area.
"I once saw a woman..."
I once saw a woman roll up to the Window and she must have been a dominatrix as she had a man in the back in a leather outfit and a rubber pig mask. I can only imagine that was his kink to get embarrassed at a KFC drive through.