What does President Obama’s phrase “We don’t need to spike the football” mean?

President Obama made the following statement regarding his decision not to show dead body of Osama bin Laden to the public:

"I think that Americans and people around the world are glad that he is gone. But we don’t need to spike the football. And I think that given the graphic nature of these photos, it would create some national security risk."

By following the definition of the word, “spike the ball” by SportsDefinitions.com – "The quarterback throws the ball straight to the ground instantly after a snap" - I can vaguely guess what the president meant by the line, “We don’t need to spike the football.” But I would like to know exact meaning of this phrase. Can somebody put it in more forthright expression?

I think what he's referring to here is the act of a football player who achieves a touchdown, and thereupon having scored a goal, slams the ball into the ground as an ostentatious display of victory.

That's a "spike" and can draw a penalty for "excessive display of exuberance."

"Spike the football" used by President Obama here means "show off".

Here are some similar expressions I would use as a non-American.

We don't need to do a victory dance.

A victory dance is a celebration of victory. Like "spiking the football" it is a display of victory that could be viewed as unnecessary or excessive.

The following two fit the concept but are slightly different because they both have a subject ("him") whereas yours doesn't have to. So you'd have to rephrase to use these in the situation above, as the "loser" is deceased; however, I thought they might still be helpful for future viewers.

We don't need to rub his nose in it.

"Rubbing someone's nose in it" refers to drawing attention to someone's loss, mistake or downfall. You might be the victor, as in this example, or you might not.

Related, but not quite equivalent:

Let's not kick him while he's down.

This refers to doing something negative to someone when they are already "defeated" in some way by other circumstances (of your doing or otherwise).