We had a boxer mix named Sissy, who was adopted from an SPCA shelter in CT. She was 1.5 yrs old and we were the third owners she had. She was the brightest dog I have ever had. Her only failing was an antipathy for paper boys who came to the door; apparently had been mistreated by a teenaged boy at some point in her past. We didn't know what mixture she was until I was walking her in a park one day and someone came up to me and said they had a boxer mix who looked just like her and wanted to know where we had gotten her. As I said, she was a great dog, and I'd get another one any day. Have a golden lab now, who is a very pretty box of rocks with not enough sense to come in out of the rain. She's trainable, but I have to do it every day.
That must be a "boxer thing" because my Boomer does the thing. 
