If your Facebook profile is cluttered by ‘friends' you don't even know, but you're not quite sure how to get rid of them politely, a comedian in the US is giving you an opportunity.

Jimmy Kimmel, host of Jimmy Kimmel Live!, is holding his second annual National Unfriend Day, encouraging Facebook users to cull their friend lists back to contain only people they actually consider friends.

"It's like spring cleaning, but instead of trash, you're throwing out people,” Kimmel says. This year's campaign phrase is 'Un for all and all for un'.

Kimmel has also come up with a list of faux-pas to help pick out the most unfriendable Facebook users, including posting pictures of pets, food or sunsets, using the phrase ‘OMG, my friends are the best', or sharing opinions on gay marriage (no matter what those opinions are).

You can follow Kimmel's campaign on Twitter via the hashtags #NUD or #NationalUnfriendDay.