Raging Stiffie/Playing With

Basic Trope: An erection
Played Straight: Bob thinks about his Love Interest (or is physically stimulated) and gets an erection.
Exaggerated: Bob's boner lasts for several hours.
- Or is abnormally big and obvious.
Inverted: Alice and Bob are having sex and for whatever reason(s) (he's not physically attracted to Alice, guilt, too much alcohol, health problems, meds he's on, etc.) Bob can't achieve an erection.
- Alternatively, Alice's nipples are visible through her shirt.
Justified: Bob is sexually aroused
- Bob just woke up; it's just a hormonal response that doesn't really mean anything
- Bob is taking vasodilators (such as Viagra)
Subverted: Bob watches Alice dance sexily, but his pants are still flat.
Double Subverted: But a cowlick on his head stands up
Deconstructed: If Bob's erection lasts too long, it can have serious medical implications. Also, since Finagle's Law dictates that this sort of socially embarrassing thing will happen at the worst possible time, it could cause embarrassment.
Reconstructed:
Parodied: Bob has Pants-Positive Safety, and a bunch of people are staring at him. He reaches in...and pulls out a gun.
Lampshaded: "Is that a gun, or are you just happy to see me?"
Averted: This issue is simply not dealt with.
Enforced: Rule of Funny, Rule of Sexy
Invoked: Alice tries to seduce Bob by getting him aroused.
Defied: Bob wears a garment that will prevent erections and/or tries the Think Unsexy Thoughts method.
Discussed: "Did you see Bob's presentation, or were you too distracted by his, ahem, 'problem'?"
Conversed: "What's the big deal? Guys get erections...without them, we wouldn't be here!"
Played For Laughs: Bob gets an erection, and must make his way home without being seen...amid lots of hot girls and Freudian imagery.
Played For Drama: Bob gets an erection during a particularly embarrassing time.