What shall I say to a nurse who giggles?

My doctor has a new, very young assistant—I assume she’s a nurse: she’s the one who checks weight, asks what I’m there for, tells me how far to undress, etc.

She giggled when I emptied my pockets before getting on the scale. She giggled when she helped me onto the examining table. She giggled when she gave me a drape.

This is inappropriate and I do not like it. People feel vulnerable enough when visiting a doctor’s office without feeling like they’re a source of amusement for the staff.

I know that I can come across as being very severe. That’s not my intent; I just want to get the message across. What do you suggest I say to this youngster to make her aware of this probably unconscious habit without traumatizing her?