I think this is hilarious for Sharan. But can I say, completely off topic, that I find these sorts of gendered euphemisms for assertive women to be so completely patronizing, and a way of keeping women 'in their place.' Wy must I either be categorized as a bitch or a firecracker? You would never see a guy wearing this shirt. He's allowed to be assertive, in whatever way he pleases.
Sorry for the off-topic rant; I think that buying t-shirts for my 6 yo girl and 8 yo boy has really opened me up to the gender roles we 'allow' for with both men and women.