When Frodo, Sam, Pippin, and Merry set off into the Old Forest on their journey east, Fatty Bolger remained behind. The unsung "fifth Hobbit" feared to go toward the peril that the other four were heading into. But he was a faithful friend of Frodo's nonetheless, and his often overlooked role was to stay back at the house Frodo had purchased in Crickhollow, carrying on the facade that Frodo was living there and simply keeping to himself. He even kept some of Frodo's old clothes to help maintain the illusion.
On the night that the other Hobbits arrived in Bree, a "brooding threat" permeated the darkness of Buckland and around the house at Crickhollow. In the hour just before dawn, three Black Riders descended on the house. They were even polite enough to knock:
"Open, in the name of Mordor!" said a voice thin and menacing.
At a second blow the door yielded and fell back, with timbers burst and lock broken. The black figures passed swiftly in.
If you visit Crickhollow, and you certainly will if you do Chapter 7 of Volume 1, Book 1, you can see the broken door and the dropped Hobbit-cloak, and have a chance to chat with Fatty Bolger as well.
Sources: The Fellowship of the Ring