For the older crowd I've been thinking of something less over-the-top: something short and tasteful like "I support breasts."
And for militant righties I'm considering a t-shirt/body armor hybrid, where the upper chest would be woven chain-mail and there'd be metal spikes over the nipples. Message? Maybe: "All your breasts belong to us".
Feel free to use/say any of these phrases during October without paying me (I AM trying to help, ladies! but after this month they get copyrighted and its a nickel a shot!), and if you do feel like making a donation, send it instead to the CBCN at firstname.lastname@example.org.