In reply to:

The mere lift of an eyebrow can signal killingly funny irony if you know what you're seeing.

...and this is where I get to insert mycterismus again.

Edit:

I just want to insert the passage below from a rhetoric site many of us here use as a reference. The reason I'm doing so is purely as an interesting point of sarcasm defined as a 'bitter' form of irony. I'm not doing so to say in any way whatsoever that I agree (or disagree) with the point--just that it's an interesting point in that we've discussed at length the difference between irony and sarcasm:

sarcasm


sar'-kazm from Gk. sarcazein, "to tear flesh, to speak bitterly"
sarcasmus, amara irrisio
the bitter taunt



Use of mockery, verbal taunts, or bitter irony(emphasis, mine).

Examples
If you be the son of God, descend from the cross —Matt. 27

In the following passage Cleopatra taunts her lover Antony when a messenger comes from Rome with possible news from his wife or orders from Caesar:
Nay, hear them [the messages], Antony.
Fulvia perchance is angry; or who knows
If the scarce-bearded Caesar have not sent
His pow'rful mandate to you: "Do this, or this;
Take in that kingdom, and enfranchise that;
Perform't, or else we damn thee."
—Antony and Cleopatra 1.1.19-24

Related Figures
irony
mycterismus
asteismus