By the time the Doctor realizes that the juice he's been drinking is mildly toxic, it's too late for Rose and Jack to do anything but get him back to the TARDIS.
They barely make it to the bathroom in time; he stumbles to his knees and throws up everything in his stomach. Jack stands by the door, looking a bit green himself.
"Go on then," Rose says. "I don't want to have to deal with both of you being sick."
She rubs the doctor's back as he's sick again. "And you without any hair for me to hold back."