WATCH: Ariana Grande Surprises Sam Woolf on ‘American Idol’

Earlier in the show, Sam Woolf told Ryan Seacrest on American Idol that his celebrity crush is Ariana Grande. Halfway through the show, right before his performance, guess who showed up to chat and give Woolf a hug … We’ve never seen Woolf’s face so red.

Later on in the show, Grande appeared again, but this time she was backstage with Randy Jackson and Ryan Seacrest to talk about her new song “Problem.” And then, a fist bump from Grande apparently got rejected …

Grande laughed it off and was very sweet.

Grande wasn’t the only big name to stop by tonight’s show though: