After Max tells Booster he's invited to join the league Boosters' thrilled. So much so his mood underwear turns from the previous red rage to the white light of life...or the colorist messed up. Whichever. He is in such a good mood that he floats with his crotch near Maxs' eye level. Yeah. Max makes certain Booster doesn't alert the press to this development although Booster has to ask if the league pays it's members. Max tells Booster not to make him regret his decision. Booster huffs a little over his answer before thinking it's still a pretty sweet deal and hey Black Canary might be single.
Oh yeah, and Booster wanted to be chairman of the league despite never being on a team of superheroes before. He was so shy in the first few JLI issues and that's not surprising, he was starstuck before he even entered the team.