At the end of the video, a "2-1" score was updated as a cheeky nod to the ongoing trolls the pair do to each other.
"A birthday card might have been easier. Happy Birthday @remcelhenney," Reynold tweeted alongside the video.
The Deadpool actor also encouraged Wrexham fans to chant the song at matches: "Would be a real shame if this became a @wrexham_afc Racecourse chant."
As things currently stand, Wrexham are at the top of the National League, and if they remain there the side will be promoted to League Two - so it's easy to imagine fans chanting McElhenney's dedicated surname song if they achieve this.