Robert Downey Jr. makes fun of Tom Hiddleston's "I Heart T.S." tank

Tom Hiddleston joined Instagram on Monday, and he's already getting ragged on by "Avengers" co-star Robert Downey Jr.

Just hours after the "Night Manager" actor joined the social media platform, he got a warm welcome from Downey, who wrote, "Join me in welcoming the biggest T. Stark fan of them all to Instagram! @twhiddleston."

• Tom Hiddleston on Taylor Swift: "It's not a publicity stunt"

Downey posted a photo of Hiddleston wearing the now-infamous "I Heart T.S." tank-top -- Hiddleston is dating Taylor Swift, in case you missed it.

But Downey seems to believe the tank is for his "Avengers" character, Tony Stark.

Somebody should let Swift know.

In:
• Taylor Swift