Robert Downey Jr. Welcomes Tom Hiddleston to Instagram With a Little Friendly Shade

The 'I heart T.S.' shirt will haunt Tom forever.

Who says friends can't give each other a hard time?

In case you haven't heard, Tom Hiddleston is on Instagram now, and the 35-year-old actor's Avengers co-star, Robert Downey Jr., welcomed him to the social media platform on Tuesday, by teasing him about that now-infamous "I heart T.S." shirt from the early days of his whirlwind romance with Taylor Swift.

"Join me in welcoming the biggest T. Stark fan of them all to Instagram! @twhiddleston," Downey, Jr. wrote, joking that the "T.S." inscribed on the shirt stood for Tony Stark a.k.a. Iron Man, who the 51-year-old actor plays in several Marvel franchise movies.

WATCH: Tom Hiddleston Joins Instagram, and His First Post Will Definitely Make You Smile

We gotta say... only makes us love the tank top more!

As of yet, Hiddleston hasn't taken to his Instagram to respond to the shade. In fact, he's only made one post at all so far!