I take it as obvious that signaling is an important function in many human behaviors. That is, the details of many of our behaviors make sense as a package designed to persuade others to think well of us. While we may not be conscious of this design, it seems important nonetheless. In fact, in many areas we seem to be designed to not be conscious of this influence on our behavior.
But if signaling is not equally important to all behaviors, we can sensibly ask the question: for which behaviors does signaling least influence our detailed behavior patterns? That is, for what behaviors need we be the least concerned that our detailed behaviors are designed to achieve signaling functions? For what actions can we most reasonably believe that we do them for the non-signaling reasons we usually give?
You might suggest sleep, but others are often jealous of how much sleep we get, or impressed by how little sleep we can get by on. You might suggest watching TV, but people often go out of their way to mention what TV shows they watch. The best candidate I can think of so far is masturbation, though some folks seem to brag about it as a sign of their inexhaustible libido.
So I thought to ask the many thoughtful commentors at Less Wrong: what are good candidates for our least signaling activities?
Added: My interest in this question is to look for signs of when we can more trust our conscious reasoning about what to do when how. The more signaling matters, the less I can trust such reasoning, as it usually does not acknowledge the signaling influences. If there is a distinctive mental mode we enter when reasoning about how exactly to defecate, nose-pick, sleep, masturbate, and so on, this is plausibly a more honest mental mode. It would be useful to know what our most honest mental modes look like.
In that case, parallel reasoning eliminates anything taboo. We signal our acceptance of community norms by avoiding taboo subjects. We might tell stories to make it less obvious that conformity is an end in itself: "intelligent people resist the temptation to swear and find more effective ways to express themselves," cf. George Carlin and his seven words.
Fight of flight responses seem like a pretty clear case. Until the 20th century, most military engagements were won by putting the enemy's troops to rout and then destroying the fleeing army in detail. That suggests many find it preferable to risk total disgrace, and possible death later, to be able to run away from an immediately dangerous situation. (cf. The Red Badge of Courage, Spartan women saying "come back with your shield or on it.") Other extremely intense situations, like a parent protecting the life of a child, would probably work the same way.
We're told it's a bad idea to go into business with friends because we tend to overestimate the likelihood that they will remain loyal to us. Also, we're sometimes willing to put up with the opprobrium of friends or relatives for a potential mate. Obviously signaling is extremely important in business and mating, but we will ignore it if the price is right.
Actions taken under the influence of drugs or alcohol might count, although there's a wide range of behaviors to sort through. In college I knew a lot of people who drank heavily and publicly so that they could be (or feel, or feel perceived to be) signal-free for a while. There's also the narrative that East Asian societies are socially repressive but don't hold individuals responsible for their behavior while drunk, so binge drinking in groups is a common way to relieve stress. I have no idea whether it's true, but it's obviously a story about signaling. On the other hand, a guy on an acid trip, having a conversation with inanimate objects, isn't signaling anybody.
We can signal conformity by avoiding the taboo, but we can signal our independence via the taboo. Yes, running in fear to protect just our own butt may be a good example of a min signal activity.