Cheeky
What it really means
Slightly rude or playful in a funny way. British people also use it for small treats they feel a bit guilty about: "a cheeky pint", "a cheeky Nando's" — a quick, unplanned treat.
Context, tips & common mistakes
Cheeky describes minor, likeable rule-bending — and its magic use is as a licence for small indulgences: a cheeky pint (one unplanned drink), a cheeky Nando's (an impulsive meal out), a cheeky weekend away. Attaching 'cheeky' tells everyone the treat is slightly naughty, entirely harmless and pre-forgiven. It converts guilt into charm.
Applied to people, it stays warm: a cheeky child is mischievous but endearing, and 'don't be cheeky' from a colleague is mock-stern, not discipline. There is no real insult hiding in it — if a Brit calls you cheeky, you have been affectionately caught pushing your luck, and the expected response is a grin, not an apology.