Green’s Dictionary of Slang

1. an erection.

1968		G. Slatter Pagan Game (1969) 71: There was [...] Long Tack Samuels, Stiffy Cocks.
1983		Monty Python ‘Meaning of Life’ 🎵 It’s swell to have a Stiffy, / it’s divine to have a Dick.
1999		K. Sampson Powder 456: He was getting a stiffy.
2000		Observer Rev. 25 Jan. 11: He massages himself into enough of a stiffy to somehow ram it up.
2001		S. King Dreamcatcher 581: Why such an awful dream would give a kid a stiffy God alone knew.
2003		McGill Reed Dict. of N.Z. Sl. 200: stiffie/stiffy Erect penis. ANZ.
2004		Guardian Rev. 6 Aug. 13: He calls his penis [...] ‘full length’, ‘stiffy’.
2006		P. Carey Theft 93: A great stiffy, throbbing like a sock full of grasshoppers.
2016		D. Whish-Wilson Old Scores [ebook] Their chubbies hadn’t faded, which was a good thing. In all his years, Swann had never seen a man with a stiffie throw a punch.
2020		T. Pluck ‘Hula Hula Boys’ in What Pluckery Is This? (28 Jan 2024) 🌐 She [...] stretched like a cat, hips nudging the stiffies they politely bent to hide.

2. an invitation.

1982		Barr & York Sloane Ranger Hbk 159: stiffy n. Engraved invitation card.
1999		Observer Rev. 22 Aug. 14: You can understand being a bit bereft of stiffies on the mantelshelf.

3. see stiffy n.¹ (1)