Fill your boots Definition 1 of 2Pro Tip 1/3Generous Offer Used when someone is offering you a lot of something generously. It's an invitation! We've got tons of pizza—fill your boots! Pro Tip 2/3Not Literal It's not about actual boots! It means to take or enjoy a lot of something. They're giving away free books, so fill your boots! Pro Tip 3/3Casual Occasions Best used in informal situations with friends or family, not formal events. It's a casual get-together, so come and fill your boots.