to give someone a closed pass is to ignore them as you walk past them, after having been walking in the opposite direction towards each other. i.e. keeping your head down, not making eye contact.
the opposite is an open pass, in which you acknowledge the other person, giving them eye contact and/or a smile and/or a greeting as you pass them.
mate, i saw that guy that i hooked up with on wednesday night in the arts building today. it was well awkward! i was so embarrassed, i gave him a closed pass.