Remember 'This little piggy'? Batman/Bruce Wayne deserves a reward of some kind, and I'd like to think other ladies would like to do the same for their men as well, so TADAH!!!!!!
The three assembled heroes are Hawkgirl, Wonder Woman and Black Canary. Each of them seasoned fighters and well known arse kickers in the Justice League. The implication being that you'd get bit of a kicking if you insulted the singing