What does 馬になる mean

Question

I tried to figure out what this could mean, is it word play? I couldn't find any info.

Answer 1

This is a catchphrase of this YouTuber. He became famous around 2019 for his videos in which he cooks while imitating the voices of anime characters and using a lot of wordplay (オヤジギャグ) including うますぎて馬になる (which of course is a wordplay around 旨い "yummy" and 馬 "horse").

ウマすぎてウマになる（ウマすぎてウマになった）

肴が美味かったときの定番セリフ。後ろに絵文字が付くことがあるが、だいたい馬ではない（🐭、🐉…）。「優勝」と同じく、オタク構文の「そりすぎてソリになったｗ」が出所と思われる。

Here's an example of his video (the phrase in question is near the end of the video): 【牛タンのシチュー】自分を大蛇丸と信じて止まない一般男性が優勝する動画です。