By Zach Koons A real knee-slapper. The Falcons named Saints co-defensive coordinator and defensive line coach Ryan Nielsen as the franchise’s next defensive coordinator Friday, poaching the well-regarded assistant from their division rival. Nielsen will replace Dean Pees, who retired at the end of the 2022 season at the age of 73. Almost as notable as Atlanta’s hire of Nielsen was the manner in which the club’s social team announced the move. Taking to Twitter on Friday evening, the Falcons tweeted out an eye-rolling dad joke to accompany the official announcement of the hire. Be warned: what …