Scared at Jazz Band

Ok, I was going back to open the locked door so that everyone could get their instruments this morning. Well, I opened the door thinking that there were going to be kids wanting instruments, but to my horror, one of my friends and this other kid, don't know him, thought they could hide and next thing I knew, I was screaming my lungs out and then I couldn't stop laughing! I then sat down by the door I opened and almost started crying! Then EVERYONE was making fun of me because of that incident...I ask the people in jazz band if they heard that and they all stared laughing saying stuff like, "ya, first there was this big loud noise, like, someone saying 'HI!' and then we all heard a scream. After the scream, we knew what happened..." I wasn't too happy with my friend...-_-