to start to talk about sth / sb that has nothing to do with what is being discussed
drag sth / sb into sth
to start to talk about sth / sb that has nothing to do with what is being discussed
Do you have to drag politics into everything?
drag sth / sb into sth
to try to get sb who is not connected with a situation involved in it
Don't drag the children into our argument.
Definitions from the Oxford Advanced Learner's Dictionary, 9th edition