There is not as yet an adequate phrase to sum up the feeling of embarrassment and mild existential unease that comes about when you post a link on Twitter or Facebook only to be told that it has, like, been around longer than your gran.
There are, though, plenty of ready-made catcalls to lob at posters who clog up everyone's feed with year-old videos of the waving bear or *that* dog in Richmond Park. "Lameo" is one, "Hey, granddad" is a little better, especially when deployed against a hipster.
But you can dodge the cyber bullet – by visiting isitold.com. Before you upload, copy and paste the link into the central bar on the site. It will then calculate when it was first tweeted and how many times subsequently, finally giving you advice about your "cool" rating, which ranges from "FAIL" to the breathless "YOU ARE THE FIRST!" So if you don't want to be a lameo, check it before you tweet it.