Hairshirts: who's wearing them, who's not

Hairshirts used to be the clothing article de rigueur for penance and mortification. I mean, if you bust one out now, no one's going to argue that it's anything less, but to an extent they've had their moment. Beyond their famous use by ascetics, lay persons also wore them periodically to stave off the corporeal temptations, and men of note sometimes wore them under their robes. Today only the Carthusians and Carmelites can be seen wearing them--some orders banished them because donning them became viewed as obnoxious and self-serving--but now I'm wondering: what might be the modern fashion shorthand to let the world know we're being penitent. What's the modern day equivalent of the hairshirt?