Basic Submarining.

[Woodlouse2002]

If ever you find yourself invited onto a submarine here is the one thing you must do.

Carefully count the number of times you dive.
Carefully count the number of times you surface.

Add them all up and divide by two.

Now, if after that you have any left over DON'T OPEN THE HATCH!

[flyboy 28]

Aha! So that's what I was doing wrong.

[Romulus111VADT]

If ever you find yourself invited onto a submarine here is the one thing you must do.

Carefully count the number of times you dive.
Carefully count the number of times you surface.

Add them all up and divide by two.

Now, if after that you have any left over DON'T OPEN THE HATCH!

Hmmm, and here I thought you were talking about necking when on dates. I guess the rules work for the too....