Post your "OH SHIT" moments here!

When my dad pranked me and my brother because before we liked watching ghost pictures seeing if they were fake or real. Well my dad found a video he showed one of his workers before and said to us look closely at the car a ghost will jump over it, so we looked close and BAM SURPRISE!!(got that off a meme there) and I fell back like i got shot by a bullet, and I still remember that day...

Playing "Calling" with 3 friends. Suddenly my cellphone's alarm clock rang. The result was a lot of screaming and spilled drinks + 1 fell from the chair grabbed a lamp which then broke.

first time try to ride a bicycle.
everything gone fine at first.
suddenly a pack of dogs chasing me.
...reenact the scene from movie Premium Rush....

When I forgot I had an exam week starting the next day. Someone from my class asked me if I learned for my exams, after I asked him which exams he said: The exams starting tomorrow. OHHHHH SHIITT