Here’s something interesting:

• To turn up is to arrive.
• To turn down is to reject.

That is, if you take “turn” and add either “up” or “down” to it, you get a new, idiomatic phrase. The great part is that the two phrases you get this way aren’t opposites. Here’s another example:

• To dress up is to put on fancy clothes.
• To dress down is to berate.

What other verbs can you think of that have this property? Fine print:

• Both “— up” and “— down” must exist, and must have some idiomatic meaning, even if not much (“Think” doesn’t work, because while you can think up an idea, you can’t think down anything.)
• It’s okay if one or both of the forms is a compound word. (“Lay” works, because a layup is a basketball shot and you lay down a funky bass line.)
• There must be at least one meaning with “up” that is not the opposite of any meaning with “down,” or vice versa. (“Dress” illustrates this rule. To “dress down” is also to put on casual clothes, but there’s no up opposite to the “berate” meaning.)

My list is after the jump:

• We started with lie, sit, and stand.
• Get (à la George Clinton): both forms have the same meaning!
• Same goes for lock and tie.
• Pin, on the other hand, escapes from this pattern through the magic of metonymy.
• Shoot and cut have fairly violent down-forms but unexpected up-forms.
• Those who work with texts will enjoy the subtly different flavors of write, mark, and draw.
• Turn and show converge upwards but not downwards.
• Underworld alert: beat, crack and shake.
• Perhaps my personal favorite: double.
• Most entertaining combination: throw.
• Typically, the up-form is more pleasant than the down-form (e.g., let, take, and put), but that’s not the case with break.
• I can’t seem to face down to the facts.
• It was a lot of fun trying to run some of these up.
• I’ll shut up—or is that down?—now.

(“Look,” “talk,” and “step” almost made it onto the list, but I couldn’t convince myself that their down-forms were legit. I was also rooting for “move,” but I think that’s best described as a case of simple opposites.)

I think talk should definitely be on the list. To “talk up” is to promote something (advertise an event, etc), while to “talk down” is to condescend to someone.

wash is an interesting case: You can go wash up yourself, but you can only go wash down the car. Transitive vs. intransitive, in other words. At least that’s true in my idiolect; do others agree?

There’s also back, keep, and run (which has two non-opposite noun forms!). burn is in the class with lock and tie where both forms have the same meaning, as is slow, and close comes near. What about tear?

Why is it that “slow up!” and “slow down!” mean the same thing, but no one would ever ask you to “speed down”?

And how could you forget knock? (The recent movie, by the way, is excellent.)

I thought of bring where you bring up something to talk about it but you bring down someone with all your negative energy, man. Similar but not opposite, to me.

Why not “step”? The down-form seems fine to me.

My two are “burn” and “close”.

Also, I was particularly amused with the message above the comment box — “You can use HTML style tags or Markdown” — and wished it had referred to “markup”…

Note also that “turn in” and “turn out” also have meanings unrelated to “turn” or to each other.

I’m intrigued by “lay” and “off”. If you get laid, that’s good. If you get off, that’s good. It’s especially good to get laid and get off simultaneously. But to get laid off is not good.

My favorite is always “knock.” To knock up, knock off, knock out, knock over are all idiomatic and very distinct.

To continue mako’s comment, what about knock about and knock in? Curious about web resources on this subject, I found http://www.usingenglish.com/reference/phrasal-verbs/k.html. A brief sampling of other letters corroborates my theory that there are fewer down-form than up-form verb phrases.

Tim’s comment about turn in and turn out begs the question about in/out forms. “Put”, “set”, “muscle”, and arguably “get” and “go” fall in that group.