Gotta love a good Rottie! 
I had one years ago, Mongo. Just a pup, really. Lived alone in a city at the time. Was walking him late one night and a kid walking by on the other side of the street hollered at me, "Hey Lady, does your dog bite?"
I thought for a second. Not a great neighborhood. Hollered back, "Only when I tell him to!" Kid nodded and kept walking.

I had one years ago, Mongo. Just a pup, really. Lived alone in a city at the time. Was walking him late one night and a kid walking by on the other side of the street hollered at me, "Hey Lady, does your dog bite?"
I thought for a second. Not a great neighborhood. Hollered back, "Only when I tell him to!" Kid nodded and kept walking.