Isaiah McKenzie earned major props from his fantasy owners AND his family with his TD on Thursday night ... 'cause it turns out the Bills wideout did a gender reveal for his sister right in the middle of the endzone after scoring!!
Buffalo just made the revelation in a TikTok video posted Friday morning ... showing the slot receiver actually screaming out "It's a boy!" into a camera right after recording a touchdown in the third quarter of the Bills' game against the Rams.
In the video that the Bills shared, you can see McKenzie's family watching on the TV as he revealed the news.