Get the latest from TODAY

Sign up for our newsletter
SUBSCRIBE
/ Source: TODAY
By Lyn Mettler

Twitter and Instagram followers of actor Mark Ruffalo (better known as the Hulk in the "Avengers" film series) got a sweet surprise on Wednesday.

Ruffalo posted two $100 Starbucks gift cards throughout the day to both his Twitter and Instagram accounts, inviting fans to show a barcode to the barista at their local Starbucks for a chance to get a free treat as part of a new #PayItForwardChallenge.

If the $100 had already been depleted, people visiting Starbucks could then choose to add any amount of their choosing to the same barcode, thereby granting the next user a free or discounted holiday treat.

It's not uncommon for Starbucks customers to start a "pay it forward" initiative where the person at the checkout pays for the car or customer behind them. The next person is then usually surprised by the generosity and often continues the idea, paying for the person behind them in turn.

Ruffalo also challenged some of his "Avengers" co-stars like Don Cheadle, Chris Evans and Robert Downey, Jr. to pony up a #PayItForwardChallenge of their own. Actress and singer Zendaya accepted Ruffalo's challenge, posting a new $100 gift card of her own.

Several others on Twitter also posted their own gift cards of varying amounts.

One person even added a Dunkin' Donuts gift card to the mix!

Then Ruffalo continued the good deeds with an Instagram story posted Thursday, inviting followers to submit their email through a form on the story. The first 100 to do so received a gift card from Ruffalo himself to Global Giving, which allows people to donate to a nonprofit of their choice.

Instagram

Fans were pretty pumped about the opportunity to spread some real cheer this holiday season:

Clearly, even the Hulk has a sweet side. Thanks for reminding us all of the true reason for the season, Mark!