Kudos to this casting director!
Haynes, 27, will appear in the Feb. 2 episode of the Fox comedy as Mitch Grinder’s son Luke.
“So excited the news is out!” Haynes wrote on Instagram Wednesday alongside two selfies of the costars. “Can’t tell ya how exciting this is for me. Rob is the nicest person in the world & I still can’t believe this is happening haha!”
Lowe likewise took to Twitter to congratulate his “long lost TV son” on the news: “Welcome to the party,” the actor wrote.
“You rock, man,” added Lowe, 51.
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Haynes – who is best known for his roles in Arrow and Teen Wolf – couldn’t seem to contain his excitement, taking to Twitter later to rave about the news.
“Man I’m just so freakin happy. 2016 is blowing my mind already. I haven’t stopped laughing/dancing all day & I don’ plan on stopping!” he wrote.
The Grinder airs Tuesdays (9:30 p.m. ET) on Fox.