Freak out and search desparately for them while bitching at the staff for not keeping an eye on a minor.
How would you react if some random person walked up to you, took off their shirt and rubbed bacon all over themselves, calmly put their shirt back on and walk away?
Amused. (Sometimes, just for a moment, English words if they're repeated rapidly can sound completely alien to me.)
How would you react if you went to sleep in your own home and awoke in a stranger's home?