Is it true that some guys bump into girls on purpose,why?

have you ever done this? why do you think they do this?

I ask because,it happened to me couple of times and it starts to look like it was made up and not a coincidence.

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+1 y
the obvious one was when I was in class and by on the corner of my eye saw someone standing next to the door's window staring and when I reached the door and opened it I bumped into the guy who was staring at me all this time through that window until I bumped into him.

why?
Is it true that some guys bump into girls on purpose,why?
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