Lemon Sneaky
Originating from the term "Don't be cheaky! Lemon Sneaky" and was thus shortened to just "Lemon sneaky" to refer to anything remotely cheaky.

The term can be further shortened to "Lemon" or "Sneaky" singularly
Jess "When we went to town the other night, Emily got lemoned and Dan was being lemon sneaky with some guy on the dancefloor!"