The waiting period you assign to accepting a friend request on facebook, similar to waiting a few days to call someone you met at a bar.
"dude, accept that friend request... she's so hot!" "Nah man, i'm lettin that facebook marinate for a few days... she's gonna have to wait it out."
"how come it took you so long for you to accept my friend request... everyone knows all you do all day is go on facebook." "sorry, i just have a 3 day friend request marination period."