In regards to eating meat

[Bring4th_Austin]

perhaps cognitive dissonance theory would explain it.

People feel dissonance between the belief that they like animals and would never hurt them, and the behaviour of killing billions of animals. The way to resolve the dissonance w/o changing behav is to assert how much they enjoy the horror and plan to continue. The re-commitment to the behaviour is strengthened, and so their mind is able to more quickly resolve the dissonance. It suppresses the thoughts regarding the killing of animals & alleviates the anxiety. The reduction in anxiety reinforces the behaviour and people learn to just fantasize about bacon everytime a nearby vegetarian arouses awareness of the underlying conflict. By publicly committing to their behaviour, the mind is put under extra pressure to resolve the dissonance, in accord with the commonly understood social pressure effect where making a public social commitment can motivate people to stick with that commitment and making a public choice can motivate people to stick with that choice so that others do not look down on them for being wishy-washy.

This might be the case in some situations, but it seems to me that the biggest culprits in the "mmmm bacon!" expressions seem to be people who have no problem hurting/eating animals, and not the ones who are "wishy-washy." I agree with the cognitive dissonance idea, but the dissonance probably isn't always caused by their belief that they'd never hurt animals.