I've found one of my characters talks with his hands a fair bit. This led to thinking about FLAIL being underdeveloped. A few suggestions:

flail <self>:
You swat frantically at yourself.
Dude swats frantically at himself.

flail exasperated:
You fling your arms up in exasperation.
Dude flings his arms up in exasperation.

flail panic:
You flail your arms wildly at the air in a panic!
Dude flails his arms wildly at the air!

flail frustration:
You rapidly flap a hand in a sudden gesture of frustration.
Dude makes a rapid flapping gesture with one hand, clearly frustrated.

flail negate:
You wave both hands before you in sharp negation.
Dude waves a sharp negation with both hands.

flail excited:
You pummel the air with your fists, gleefully vibrating in your excitement.
Dude pummels the air with his fists, his whole body vibrating with excitement.


Similarly, SLAP could have some additional fun use with locational messaging:

SLAP (location - neck, arm, leg, chest, etc)

neck, arms, legs:
Dude slaps at his [neck/left arm/right arm/left leg/right leg]!

chest:
Dude slaps both palms against his chest. (Come at me, bro!)

abdomen:
Dude gives his belly a hearty pat. (Follow up with a good belch or dwarven grunt.)


And finally, I'd love to see more WAVE options, it seems it would lend itself well to a crapton of different gestures. A few starting ideas:

WAVE FRANTIC
Your wave your hand in a frantic bid for attention.
Dude waves his hand in a frantic bid for attention.
Dude waves his hand at [you/Person] in a frantic bid for [your/her] attention.
Dude waves his hand at [object] in a frantic bid to call attention to it.

WAVE LAZY
You give a lazy wave of your hand.
Dude waves a hand lazily [in your/Person's direction].
Dude gestures toward [object] with a lazy wave of his hand.

WAVE THOUGHTFUL
You flick your fingers absently, lost in thought.
Dude's fingers flick absently and a distant expression crosses his face.
You gaze thoughtfully in [Person's] direction and absently flick your fingers in contemplation.
Dude's gaze drifts in [your/Person's] direction and his fingers twitch absently.
Dude's gaze drifts toward [object] and his fingers twitch absently.

WAVE PROMPT
You quickly wave a hand [at Person] in encouragement to continue.
Dude waves a quick encouragement [at you/Person].
You wave a hand at [object] and pause, waiting for something to happen.
Dude waves a hand at [object] and then pauses. He seems to be waiting for something.

WAVE REASSURE
You wave a reassuring hand [in Target's direction].
You wave a hand at [object], assured of its harmlessness.
Dude waves a reassuring hand [in your/Person's/object's/creature's direction].

WAVE SCOLD
You shake a scolding finger [at Person/creature].
Dude shakes a scolding finger [at you/Person/creature].

- Jen et cetera.