When Danielle and James Ellerby show off photos from their 2018 wedding, they have a bit of explaining to do. It’s not because the couple, who live in Halifax, England, eloped while on vacation in New York City. It’s because their witnesses were two strangers in T-shirts and running shoes.

“Who are these two random guys in tuxedo shirts?” Mrs. Ellerby, 29, said she is asked most often about the pictures.

Those two random guys are members of the running Wedding Hashers, as they call themselves and their Instagram handle. They are a group of five runners from New York and New Jersey who wear custom-made, sweat-wicking shirts that look like tuxedos. They run mostly around Brooklyn to get in pictures with as many wedding parties as possible (with permission).