Ben 10 S00 E07 Let the Games Begin

"An alter ego for every occasion."

Ben and Gwen are playing Roadkill bingo with things that are seen on the road to see who'll sit on the front seat weekly and Ben is losing, so he turns into XLR8 to place things on his card on the road. But with unexpected results, Ben loses and is grounded at the back seat for a month for cheating.