Interrupted

The worker smiled, looking to my mom. "Can I bag some crickets for you?" She asked. 
My mom frowned, finger to her lips. "Yes...."
The worker nodded, moving to open the container holding the bugs. "How many?" 
I straightened, brightening, I knew the answer! "She needs 12 lar--"
My mom whirled on me and I shrunk back, only now realizing my mistake at her thunderous expression. "Don't you know not to interrupt adults when talking?" She asked, ice in her voice as I shrank back, trying to not be taller than her, though it was impossible not to be. My growth spurt had only continued this past year, and I was well head and shoulders taller than her. "You're lucky we're in public." She continued. "Else I would have smacked you right here."
I hid a wince, moving my face into a neutral position as I stared at my toes. I hadn't meant to overstep, I'd just been trying to be helpful. But my mom never saw it that way. Which meant. "When we get home, your phone is being locked up." She turned back to the worker, who was doing her best to keep a neutral expression as well, though I could see the concern in her eyes as she glanced at me. "Sorry about that. I need 12 large crickets." My mom said. 
"Okay." The worker said quietly, quickly counting out the correct amount. 

-Inspiration from a customer conversation