Love? Love is not forever. Love dies every day.
Diamonds? Diamonds aren't forever. They're tough, but can be crushed and even burned.
Tweets though? Tweets are here for all eternity. We see the ramifications of it constantly. Tweets come back to haunt people on an almost daily basis.
Take for example...
I don't use Twitter much.
I've got a blog to come back and haunt me forever.