Has little or nothing to do with anticipated results. It's not limited to sports or competition. You can choke on an assignment for work, choke in an attempt to seduce a crush of yours. Jordan missing a free throw. You can choke anywhere, anytime.
Choking is when you had control, and failed to execute.

What happens is you are suppose to be focused on what your eyes are viewing. But your weak mind chooses to worry about something negative whether real or not, past or future.

It's bigger than that

n. A small hole in a pipe, bong, or other smoking device with a smoke holding chamber. Located at the end of the chamber farthest from the smoker's mouth. A thumb or finger is placed over the hole during the initial inhalation so that smoke can be sucked into the holding chamber. After the chamber is filled with smoke, the choke is released and the smoke sucked out of the chamber with fresh air rushing in through the carb to displace it.

being up 3-0 in a best of 7 series and still losing. (see Yankees)

A cigarette or pack of cigarettes.

Alot, numerous.

When this hot girl at work asks you to have sex in the Think Tank (conference room), then you fart and ruin the mood.

An act in which a team or a person collaspe when they are expected to win no matter what the other team does.