Green’s Dictionary of Slang

to be brave, to be plucky (cf. have a (wild) hair up one’s ass under hair n.).

1918		F. Gibbons They Thought We Wouldn’t Fight 344: ‘What do you think of the President of the United States?’ [...] ‘Say,—that guy—that guy’s—got hair—on his chest.’.
1933		D. Hammett Thin Man (1962) 32: ‘Jesus,’ he said admiringly, ‘there’s a woman with hair on her chest.’.
1962		(con. 1940s) G. Mandel Wax Boom 241: Uphill too! Man, what kind of wild hair you got?
1973		C. Gaines Stay Hungry 146: These kids now, they don’t have a hair on their ass. I’ve done it all, man, glue, mushrooms [...] I been weird every way there is.
1976		P. Conroy Great Santini (1977) 382: Brannon ain’t got a hair on his ass compared to Strait.
1981		(con. 1963) P. Conroy Lords of Discipline 196: Pig had rated me number one [...] ‘Because you’ve got hair on your ass.’.
a.1994		J. Boyle Apache Sunrise 3: The kind of team that any commander with hair on his ass would want his unit to be like [HDAS].
1995		Donahue [NBC-TV] A guy who eats nails for breakfast and he’s looking for a chance to show he’s got hair on his chest [HDAS].

1. to embolden, to make stronger, usu. used of sex, food, drink.

1912		Printing Trade News 43 122: I can put you next to Old Blossom Club, a rye that will put hair on your chest if you haven't got any, and take it off your chest if you've got too much.
1923		Adventure 44 105/2: ‘It’ll put hair on your chest!’ ‘But — ’ pleaded Edgar, desperately. The captain lurched around the table and shoved the glass into his son's hand. ‘Drink, me hearty!’.
1929		T. Wolfe Look Homeward, Angel (1930) 390: It’ll [i.e. a visit to a brothel] make a man of you, ’Gene [...] Boy, it’ll sure put hair on your chest.
1956		F.B. Vickers ‘The Pommies Club’ in Drake-Brockman West Coast Stories (1959) 29: Tough tucker, old boy. Puts hair on your chest. It’s the tucker to build an Empire on.
1960		C. Cooper Jr Scene (1996) 62: You should have been in the Sixth Precinct a long time ago [...] Grow some hair on your chest.
1980		J. McClure Spike Island (1981) 38: ‘It’ll take the blinkers off ’im, won’t it, Arthur?’ ‘Put hairs on his chest, no danger.’.

2. to cheer up, to strengthen; esp. in context of offering a drink, e.g. that’ll put hair on your chest.

1957		(con. 1944) A. Myrer Big War 426: Get these down: they’ll put hair on your sagging chest.
1958		(con. 1940s) B. Behan Borstal Boy 120: There you are, Paddy. That’ll put ’air on your chest.

(Aus.) a general excl. of approval, acclamation, ‘good for you!’, ‘well done!’ etc.

1898		Maryborough Chron. (Qld) 22 Sept. 3/1: (Jones) replied, ‘More hair on your chest, old man, if you can do it’.
1902		Worker (Brisbane) 13 Dec. 5/1: By way of encouragement a thin, cadaverous, larrikin-looking bloke ejaculated, ‘More hair on your chest, old wan’.
1924		Cessnock Eagle (NSW) 23 Dec. 7/7: People Say [...] That the toast ‘More hair on- your chest’ is not appreciated down Hughie Harvey's way.
1939		Nowra Leader (NSW) 29 Sept. 6/2: All I can say is all the more hair on your chest, Denty.
1941		Baker Popular Dict. Aus. Sl.