It really wasn't meant as an insult, just..um..well...it's the best description I could come up with, although I agree the mental picture isn't so pleasant!!
I once had a yellow lab in training that would take food out of pans on the cooker! She never injured herself, although how was a mystery. Needless to say she didn't make it as a guide dog! I was working her in town one day, her in harness and me in blindfold with a colleague following for safety. I felt her pull slightly and quickly to the left but she walked on at the same speed and on the same line as before until I heard my follower yell,"Stop!" (When you are blindfolded you react pretty quick to that!)
It turned out that the dog had walked past a child of about three years of age and stolen her ice cream cone!! How embarrassing is that?!