To pull a "kasai" is to show up suddenly (either in real
life or on social media), say Hi, and then quickly leave/disappear without a
trace. Often times interrupting a conversation
two others may have been having.
Person 1: So have you seen that new
movie about
Eagles?
Person 2:Oh yeah that was pretty great my favorite part was whe-
Person 3 shows up
Person 3: Hi
Person 3 leaves
Person 2: Fucking bastard
pulled a kasai.