Green’s Dictionary of Slang

shit a brick! excl.

also shit a brick and build a house! …and fart a crowbar! shit a pebble!
[shit v. (1a)]

(orig. Aus.) an excl. of extreme surprise, annoyance.

[US]W. Styron Set This House on Fire 465: Shit a brick, how am I going to give him any blood?
[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 17: Shit a brick, there’s fifteen and a zac on the clock already.
[Aus]D. O’Grady A Bottle of Sandwiches 89: Shit a bloody brick. Bloody dirty stinkin’ rotten bastard. [Ibid.] 206: ‘Shit a bloody pebble,’ he said.
[Aus]D. Maitland Breaking Out 125: Shit-a-brick, you only have to look twice at some of the blokes in that town to get thumped on the bloody head.
[SA]P. Slabolepszy ‘Under the Oaks’ in Mooi Street (1994) 40: Shit a brick!
[SA]P. Slabolepszy ‘Boo to the Moon’ in Mooi Street (1994) 91: spider: Fuck a Duck. jessica: Oh my God. What happened? [...] spider: Shit a brick.
[Aus]Syndey Morn. Herald 7 June 35/5: Fart a crowbar if the book didn’t go down quicker the the first cold tinnie at a butcher’s picnic.
[UK]K. Lette Mad Cows 93: Shit a brick, Alex! Maddy panicked.
[UK]Roger’s Profanisaurus in Viz 87 Dec. n.p.: shit a brick 1. interj. Exclamation of surprise. […].
[Aus]Sydney Morn. Herald 23 Jan. 18/1: ‘Ohhh, shit a f—ing brick. I have doing 60-second f—ing commercials’.
[NZ]McGill Reed Dict. of N.Z. Sl. 185: shit a brick!/shit a brick and fart a crowbar Extreme exclamation. ANZ c.1925. [...] shit a brick and build a house Exclamation, often at unexpected good luck.