Someone not to get on at. A word used in conjunction with the phrase 'don't get on at' in verbal combat against the grumpiest of Grandads. Beware, this is not guaranteed to ward off grumpy old farts and/or the aforementioned and much dreaded grandads.
*Grumpy Grandad feels grumpy and grumbles at Granny*
3rd Party - "Don't get on at Granny!"