Define Deffo Shaggin' Meaning

Deffo Shaggin'
A term meaning you and someone else are thinking 2 people are having sexual intercourse without your knowledge, but you can tell.

*Teacher sat at desk and is marking work*
*Another teacher enters and starts talking to the other teacher*
*Pupils turn round to friend*
"Them teachers are DEFFO SHAGGIN' look at them"
By Alisa