I've read another post with a similar tactic, but if you're getting really camped, one thing to try is to roam to another lane, and let your tower go.
Benefits:
The wave is pushed so far down your side of the map that if you can freeze there you pretty much ended your enemy's laning phase. There is no way they can CS that far down without getting ambushed.
If you're at another lane, preferably bot lane, you and your jungler can turn your bot lane into a 4v2, and take their tower, and possibly dragon.
Your opponent will roam as well, giving you a nice couple waves of relevitely safe farm to catch back up. You can play safe from there, ward up and enemies that mess with you that close to base will have nowhere to run.
Cons:
Your enemy will get first tower blood if you can't hold the tower and buy your team time to knock down one of their towers and get first tower blood.
If you do this too late and after you died too many times, you'll end up setting a fed enemy loose on your team, and you can't help because you'll get deleted. So you're stuck farming to catch back up while your teams' getting their butts kicked.
Your team may not get your strategy and might flame you for leaving your lane and giving up your tower.
So yeah, that's a potential thing to do when you're camped. Stay safe and try not to let your enemy get fed, and once your team knocks down a tower, which should be easier since you're getting camped (which means their jungler is focused on you instead of applying global pressure), then you can let tower go, and let the wave come to you, farming with relative ease.