ASL has idioms as well. As with any language, sometimes the idioms doesn't tranlate or have the same cultural meaning in another language. I will try to describe how to sign them.
ASL Idioms
TRAIN ZOOM- "That ship has sailed"
FISH SWALLOW- gullable
PATIENT TOILET- can’t wait any more
BIG MOUTH - (signed like TABLE, but the arms open and close)
means:talks too much or a person who moves their mouth too 

much
THINK-HEARING: sign HEARING at forehead. Shouldn't be used by 
hearing people, means "you think/act/kowtow to hearing people"
ZERO-BRAIN- Zero on forehead "stupid, ignorant"
SICK-ON-THAT- sign SICK then directionalize it. "ick"
STICK BRAIN- 8 handshape, opened, then close on forehead. "I will 
remember that!
N-G- sign N then G "no good"
T-B- sign T then G "too bad"
THIRSTY- means lust
DROOL- lust, want that a lot
I, I, I, I- signed at waist- means brag
PEA BRAIN: G hand shape at forehead, twists and touches head- means stupid
Daffy: Y on forehead- flaps
Brown noser- B handshapes rub side of nose, palm out
Nosey/big nose- outline nose, exaggerating it largely
BS- arms crossed, top hand with index and pinkie extended, bottoms showing pooping.
By a hair- pull a hair (not literally!)
Riding the fence-
‘love it’- kiss your fist!
boiling in anger
blow my top
waste money- "toss money" out of pockets
talking to self- "I" handshapes circle from side of face to meet in front and tap
blow right by me
blow… nothing
THINK DEAD- I couldn’t believe it
SUPPRESS
Keep mum: PRIVATE then second hand covers 1st.
Learned my lesson, blew up in my face: O handshape on nose, to 5
HUH?
So much to think about: K, both hands, wiggle in front of eyes
Push out of my mind: use 4 handshape
Dwell on: think, obsess
Right around the corner: F on nose, move out and down, P/O down
Extremely complicated: wiggle X in X movement crossing in front of body
Pretend: open and close flat O on side of mouth- palm orientation, back
Barely getting by: 8 alternates off chin
Budget money- tight circle of flat Os
Holier than thou: 7 off mouth, like innocent
I am out of here: G moves to closed G
THINK YOURSELF - you decide
YOURSELF, YOURSELF: Take care of it yourself:
Waste Time: throw away time
Gobble up
Drink too fast
HA HA behind head
Falling in love
Soft heart
Tough heart: F handshape tap at heart
Fooled me: A handshape hits 1 HS
Rolling on the floor laughing
Nothing to do: ear and lip flip
Fall Asleep: As hit
Far: wiggle 1 way out there
WOW S hand at eyes
Need proof: pull eyelid down
Expert: same as neat
Not my responsibility: flick 8s at shoulder
Missed it: 4 hand down in front of face
Passed me by: 4 hand up and in front of face, WHEW
Nothing to it: F hands back and forth
Puzzle
Jump for joy
SLAM index or middle finger slam between finger of other hand
Over my head
Butt heads: Confront using Y hand
I have no idea: ???? with 4 hand
All Gone: Blow on hand
Touch finish: been there
Disgusting: upset stomach
Shock: jaw drops with bent V
Finish, Zero, Finally are sometimes called idioms, but they are not true idioms.
They are used often, but the meaning doesn’t change.
FUNNY-NONE just means not at all funny
SEE-NONE means I didn’t see it.