stole my idea of changing it and using it another way
As long as slogans and graphics have existed people have re-worked them to say or look different than their origional base form. For example, AYBABTU.
Saying any one stole your idea of changing a slogan in to some thing else is just rediculous.
Darwin may have seen neil's alteration before your (or after) but it may have been neils slogan that took him to his current anti-thorne posters and stickers.
As far as I can tell, Darwin is thanking neil for the "don't let ... take your penis" part of the slogan re-design.
Further more, last time I checked, any one can use any one elses art work or graphics as long as the piece is altered at least 80% from the orriginal work in its appearance. In all manner of legal terms what happened here is totally legal.
Neil, you have no right to take any credit. You shouldn't even be using it.
You don't even have enough respect to show credit where it is due.
While he may have taken the exact graphic directly from you (I do not know if this is true) and if he did, then that is not right, but this is the internet and being such I have noticed that unless you publish a message which says no one may use the graphic unless they have your permission, people will still take them.
All in all... I think that Darwin already thanked both Ozzy and Neil, regardless of who had the disputed idea, so instead of being pissed off and arguing about it who ever is arguing should just say "you're welcome." :-)
Of course... if any one is up set about their intellectual property being used with out their consent, you can refer to the "has been changed more than 80%" rule that most artists stick to for reasons like these. Legally no wrong I can see has been done here.
*****EDIT*****
Ahh... Ozzy's sig is now showing up (before it was not) and I see now what you are talking a bout. If you would like to get technical about ideas being stolen, I think I saw that on a vehicles bumper over the summer.... but I could be wrong. I don't see what all the fuss is... they all look like funny ideas to me :-)