Get mixed up with him - Idioms by The Free Dictionary
get mixed up with (someone) (redirected from get mixed up with him)
get mixed up with (someone)
To become involved with someone dangerous or troublesome. Don't get mixed up with a dangerous crowd like that.
be/get mixed ˈup with somebody be/become friendly with or involved with somebody that other people do not approve of: I told her I didn’t think she should get mixed up with that group, but as usual she ignored my advice.