I remember this comedy show we went to one time the guy was going on about "black people are like this and that..." We were sitting in the front row and her turns to me and says "you're black... You know what I mean. 
" I responded " I'm Ian... And Ian doesn't know what you mean." Ruined his set for a solid 5 minutes.  

 I frequently find myself in interactions like that. Which is frustrating. 

“Well you’re a white male so you think x, y and z” 

I don’t think any of those things. 

“Yes you do” 

No I really don’t. 

 Assuming is a dangerous weapon