Eddie51 - when my husband (of 48 years) was just my boyfriend, he used to say you know/you know what I mean frequently. I got fed up with it so each time I would pick him up on it (he was pleased as a young man, he wanted to get on at work and didn't want to be irritating). So if it was 'it's raining, you know what I mean'. I would ask him to explain. Maybe if you asked your colleague 100 times a day to explain exactly what he meant, he would get the message. It didn't take long for my boyfriend to get out of the habit.