Personally, I just think "this tastes good and I don't want to stop eating it." Often I will consciously try not to think about anything so as to keep guilt at bay. I fantasize about binging regularly, about just eating and eating and eating to the point where I can't physically eat any more, and then waiting for my stomach to produce room for more so I can keep eating. I have never allowed myself a truly epic binge like that - the worst I've had was going through a whole 250g jar of natural peanut butter in one night. I know deep down that even if I ordered and ate an entire large pizza or something, I wouldn't feel like it was enough.
There are also lots of justification-type thoughts centered around overeating and binging, like "I'm going to gain but I'll just lose it again" - which I do - and "I'm a perfectly healthy weight" - also true but everyone knows binging is unhealthy disordered behavior.