This is a prefix, that is added onto anything that you are doing/having, without permission, when at work, or in some type of lesson, where rules are to be followed.
1) (when working outdoors) Scott, go and make us a cheeky-bru whilst the boss is havvin a shit!!!
2) Rite, i'l go and roll us a cheeky-joint in the toilet.
3) I had a cheeky-spliff at work, itz always better when ur not supposed 2 be doin it!!!