[robjh]

I think companies which use weird double negative language by these options on forms aught to be penalised.

[ / ] uncheck this box if you don't not agree.

[threedaymonk]

Or the ones that have two boxes, one positive and one negative:

    [x] Send me marketing emails
    [ ] Don't pass my email on to third party spammers

[grahamel]

or the ones that do something like:

    [ ] Accept terms and conditions and send me marketing emails*
    *required