Booby prize — prize given as a joke to the last-place finisher in a competition
Brainiac — a comic book supervillain (1938); a very intelligent person (1982)
Heebie-jeebies — anxiety, apprehension, jitters, the willies (1920s)
Dicing with death — taking serious risks (1940)
Step up to the plate — accept a challenge (from baseball)
It’s your nickel — it’s your turn to talk
Tintiddle — a witty retort that you think of too late
Conniption fit — sudden outburst of hysterical excitement or anger (1825-35)
Muck around — fool around or to cheat or deal dishonestly with someone
Straight as a die — a plain person or object, correct and true (1500s)
Rainforest Writer 