Friendly debate on sell out call on DP

[Tru_in_Blu]

I recall at a NUS that it was recommended that we give the sell out for the back end of a double play.

A few umpires were having this discussion.

When do you use the sell out?

1. On a routine 6-4-3 DP that's close at first.
2. On a routine 6-4-3 DP when the batter fell down in the batter's box.
3. Runner off first gets doubled up following a line drive catch by an infielder.
4. Runner on second thinks a ball hit to an outfielder will not be caught, but it is and the runner is out by 50 feet.
5. A dead ball appeal on a runner that left early on a caught fly ball.
6. A strike 'em out, throw 'em out DP.
7. Others?