An eye for an eye, a cake for a cake.
Jake Gyllenhaal, Maggie Gyllenhaal's brother and a successful actor in his own right, is also very generous. Amy Schumer, Senator Chuck Schumer's cousin and a successful comedian/actress/screenwriter herself, once Airbnb-ed his house and naturally, got drunk and had a little fun going through his freezer. While staying in his house, Schumer took a bite right out of a frozen cheesecake from Gyllenhaal's girlfriend's birthday. To pay tribute to this now-famous moment, and to match Schumer with a viral video of his own, Gyllenhaal and Colbert bit into the cake's doppelganger. Neither of them seem to enjoy it that much, but they commit to the bit.
Here's the original video where Schumer tells her side of the story from the original Colbert interview: