The Law of Diminishing Defensive Effort/Playing With

Basic Trope: A character will ignore any attack that cannot harm him. Therefore, anything that he bothers defending against or evading is dangerous.
 * Straight: Bob is Immune to Bullets. When the Mooks shoot him with normal guns, he walks right through the gunfire. When the Giant Mook takes out an anti-tank missile launcher, he has to avoid it.
 * Exaggerated: Bob laughs off an anti-tank Macross Missile Massacre, but desperately finds a bunker when The Dragon calls in a tactical nuke.
 * Justified: Bob knows what can and can't hurt him, so by ignoring attacks that aren't threats to his well-being he can maintain his focus on the bigger situation and look out for things that would harm him.
 * Inverted: Bob desperately defends himself against the harmless bullet, but relaxes when a missile is aimed at him
 * Subverted: The bullets can't hurt Bob, but they can stagger and stun him long enough for the mooks to retreat or get better firepower.
 * Double Subverted: Which he still laughs off, until the Giant Mook takes out an anti-tank missile launcher, that is.
 * Parodied: When the enemies start attacking, Bob sits down and calmly has a Spot of Tea as their attacks strike him to no effect.
 * Deconstructed: The enemy throws a bunch of different kinds of weapons at Bob, and by observing which ones he does react from they can infer what kinds of weapons will harm him, thus eventually using those particular weapons against him.
 * Reconstructed: Bob one-ups them in the I Know You Know I Know department by dodging harmless attacks, giving the enemy false information which he then uses to his advantage when the time comes.
 * Zig Zagged: Bob sometimes defends and evades and sometimes does not; there is no way to tell from his behavior whether an attack will be effective against him.
 * Averted: Bob always defends against and evades enemy attacks.
 * Enforced: "We need to show how resilient the hero is."
 * Lampshaded: "Y'know, he isn't even trying to defend himse- op, here comes Missile Mike. Now he's runnin'"
 * Invoked: Dave has newly acquired Bob's Nigh Invulnerability. On their first mission together, Bob tells him not to worry about the Mooks' normal attacks.
 * Defied: Attacks that can't kill Bob still hurt, so he wants to avoid them all.
 * Discussed: ???
 * Conversed: ???
 * Played For Drama: We see the Mook Horror Show as the Mooks desperately keep on Shooting Superman, knowing that they have to keep Bob busy even if they cannot actually hurt him. When the attack that can actually hurt Bob comes into play, the Mooks are rallied.
 * Played For Laughs: Bob survives an escalation of firepower without even flinching, until he gets to the final item -- which is patently ridiculous, such as a feather duster.