Butthole Child

Lady comes in with her kid, he's about 7 years old. (Thank goodness she left the daughter at home, the daughter is a demon and the mom gets SUPER PISSED when I tell her to stop doing stuff like climbing on glass shelving!) The seven year old boy child starts jumping around all over my counter and display cases, so she picks him up like he's a toddler and sits him on my counter. The first thing the kid does is start messing with my stuff on the counter and trying to dump my paper clips and staple with my staple. I told him to stop it. Then he starts messing with the box cutters that are on display...purposely up there where kids cannot get them...and I told him to put them down. He is sitting there kicking the shit out of my counter, messing with things, slurping a soda, you name it. Finally Mom concluded her business so I reached over and tickled Junior a little bit, he yelled, "YOU BUTTHOLE!" and jumped off my counter.
Would any of you be surprised that his mom GUFFAWED and was beside herself at how funny her seven year old sounded, calling someone a 'butthole'? The kid's dad is a jailbird so I guess Junior is just prepping for the day he's in the pokey. What class.