1. Family Reunions. You see, there's something inherently difficult about trying to remember the names of thirty-some relatives that you see all of once a year. In consequence, there's a lot of, "Hello!...you!..." going on, which is an instant recipe for awkwardness. And that's not including the nearly unavoidable "You've grown so much!" comments, which cease to be a compliment around age 13 and instead turn into a worrisome remark that sends probably 95% of teenage girls running to the mirror just to make sure...
2. Cases Where Life Imitates Art. I'm positive that people-who-are-not-me have also had the unsettling experience of realizing that Circumstance Whatever bears a striking resemblance to Novel Whatever. What was really surprising was when an entire conversation unfolded that was nearly a perfect paraphrase of another conversation out of a certain novel. It was highly unsettling, and made for a very interesting journal entry. And no, I won't tell you what it was, mostly because I scarcely remember it myself. Rest assured, though, that it was very entertaining.
3. Moments of Awkward Affection--Familial Edition. Much like #1, and often taking place at such, you feel quite strongly that you should probably know this person that is expressing heartfelt sentiments towards you, and yet...just...can't...place...it...
3.2 Moments of Awkward Affection--Romantic Edition. Often juxtaposed with #2. Times when you're really, really sure that someone in your presence is flirting very heavily with someone else in your presence, and there's absolutely no way you, an innocent bystander, can possibly get out of it. Amount of awkwardness is usually directly proportional to the amount of time that said flirting takes place. Extra awkwardness if the flirter is getting no response from the flirtee, and therefore increases the amount of flirtatiousness to the point where you'd think the flirter was suffering from either seizures (from the rapidity of eye-blinks, undoubtedly intended to showcase the eyelashes of the flirter) or a mental disorder (from the various contortions in position intended to demonstrate the attractiveness of said flirter). Frequently, the only solution for this is to incredulously watch, laugh it off inwardly, and then write a blog post about it.
4. Making a joke about some piece of classic literature that, to you, seems patently obvious, only to have the receiver of the joke stare blankly at you for fully ten seconds before you break down and mumble something explanatory about the joke. This is frequently accompanied by a deep feeling of embarrassment at having made what you thought was an obvious joke and, thus, also embarrassing the receiver of the joke, as well as resentment that your joke-receiver didn't get THE MOST OBVIOUS JOKE IN THE WOOOOORLD. (this is frequently preeminently awkward only when the joker has been deprived of coffee, and therefore is utterly unreasonable in nearly every imaginable way)
5. Laughter At Inappropriate Times. This can be either obvious awkwardness, such as when someone in church misreads "immorality" as "immortality" or the like. In that case, though, it's less potent awkwardness because everyone heard it and everyone, then, is feeling awkward. The Most Potent Awkward, however, occurs when it's actually rooted in your own thoughts and feelings. For instance--if, hypothetically, someone made a reference that you found wholly ironic, and you were just barely restraining your laughter, and then looked up at a friend only to see a similar pinched look indicative of restrained chuckles, resulting in not one but two fits of half-choked laughs--yeah. Like that. Of course, full Awkward Potential is only achieved afterwards, when the person who expressed joy looks at you as if to say, "Was it something I said?" resulting in renewed hilarity.
5.2 Laughter At Inappropriate Times--Being Made To Laugh While Taking A Drink. Self-explanatory.
There are, obviously, many more subsets of Awkwardness, but these are the ones that--for one reason or another--seem to float around me half the time, and I have no idea why. By far the most obvious, however, is the latter, because--well, have you ever heard someone break out laughing when they had been physically clamping their jaw shut? It's not pretty. And it can hurt your neck. Plus, it's really hard to explain to people why you burst out laughing in the middle of a prayer, or a dramatic reading, or a conversation about the stock market.