Woman puts Mentos inside Diet Coke bottle so the mints will fall in when someone tries to open it. Man opens the bottle, he gets sprayed. Girl explains the practical joke at the beginning.
Teen boy pours cold water on teen girl in the shower, the curtain falls. Action also in slo mo. Practical joke. No recovery. College / dorm.
Young man scares woman with a mask. Woman screams when she sees man. Night.