Most annoying travel habits

I consider myself a rather calm person, and someone who can brush off most things. But I swear to God when someone in the row behind me on the plane stands up and has to use my chair/headrest as the end all be all of balance to hoist themselves to a standing position, taking me for the ride of my life in a sedentary seat, I see the face of the devil.

That and ppl who block the boarding now lane when they can’t board yet…

What are the most annoying habits you see people do when traveling?