Beth: Wow, that was close! Old Mr. Johnson almost saw me writing on his car window with soap.
Tom: I see you’re up to your usual shenanigans.

“Shenanigans” are tricks or trouble. They can also be dishonest behavior. For example, “The politician lost the election after the public found out about his shenanigans.” Shenanigans are always plural. It is unusual to hear of a single shenanigan.