Serious movie scenes that inspire inappropriate laughter

[The Great Owl]

I'll get the ball rolling... Beware potential spoilers.

• The scene in Jaws when the corpse appears while Hooper is removing a shark tooth from underneath the small boat. Richard Dreyfuss's facial reaction cracked me up when I first saw the movie during childhood, and it still cracks me up.

• A serious moment in Alfred Hitchcock's Spellbound where a character is remembering a horrible traumatic incident from his childhood.
  [Show spoiler] As a boy, the character slid down a stairway rail, kicked his brother at the bottom of the rail, and saw his brother impaled on a spike fence underneath bottom of the rail.
  I am probably a bad person, but I cannot help laughing during this scene.

• Jack Black's delivery of the "It was beauty killed the beast." quote at the end of Peter Jackson's King Kong.

• Every single death scene in the Final Destination movies.

Now, I usually suppress laughter during such moments in a theater, because I never want to be That Guy who laughs in the theater during an intentionally serious scene, but this takes effort at times.