Your Grandmother probably wondered what was so funny. If you are "old" now she could have been from a time when the police in small towns doubled as the Fire Brigade.
And I always liked that grand old Scottish word, "houghmagandie". It refers to an activity in which a certain Scots poet revelled.
I occasionally drop it into a conversation just to see how many listeners catch it.
For the Sassenachs and others who speak a different tongue the word translates as "recreational sexual intercourse".