As long as I'm on the subject of pet peeves, I'll swing from a linguistic one to a liturgical one: the practice of holding hands during the Pater Noster (Our Father) at Mass.
This takes several slightly different forms. Most of the time, people in the pews join hands with whomever is to their right or left. Sometimes this extends across the aisles, or from one end of a pew to the one behind them, so that the entire congregation is linked. Sometimes the priest(s), deacon, and altar servers join hands up on the altar as well.
It's a very widespread practice, but I'm not sure why. I'd say at least some of the congregation has done this in nearly every parish I've been to, yet nowhere in the rubrics of the Mass (i.e. the instructions for how Mass is to be celebrated) does it say to do this. We stand and sit and kneel at various times during Mass because the instructions say to. So why did we ever begin to do this? I'd be curious to know, but that's not my main point here. I'm going to offer a few simple arguments against this practice.
First, as I just mentioned, the rubrics of the Mass do not say, "At the Pater Noster, the congregation then joins hands." There is no prescribed action for the congregation at this point of the Mass; we're simply to pray the Lord's Prayer together. You could try to make the "it doesn't say we can't" argument, but that's a bit silly since instructions tell what to do, not what not to do. And if the instruction of the Mass doesn't say to do anything there, then it's to be understand that no extra action is to be taken.
Second, I would say it's a confusing gesture in the context of the liturgy. There are certain things that are unique to the different participants in their particular ordered roles in the Mass: the deacon calls the people to prayer, the priest prays to God on behalf of the congregation, the people respond in assent and praise and thanksgiving. One of the gestures that marks out the priest's unique role as intercessor in the Mass is the orans position, the outstretched hands that one sees at the Collect, or during the Eucharistic Prayer, or during the Pater Noster. The congregation is never instructed in the rubrics to use the orans gesture during the Mass. Using this gesture, and joining hands while doing it, is a confusion of the roles of the priest and the congregation; the congregation should not take on that which is proper to the priest, nor the priest that which is proper to the congregation.
Third, I would ask for the positive reason for doing this (i.e. don't just say "Why shouldn't I do this?" but tell me why you want to do it at all). The best I've heard is something to the effect of "It's a sign of our unity as a community in praying to God." OK, that's not bad, I'm all for signs of Christian unity, or common union, or communion, if you will. But think about it when this prayer takes place: we've just finished the Eucharistic Prayer, by which is effected the transformation of bread and wine into the Body and Blood of the Lord Jesus Christ, the Eucharist, Holy Communion. That is our sign of Christian unity. That is our sign of communion. And even better, it is an efficacious sign--by receiving it, we actually becoming united with one another, mystically and spiritually, really and truly, not merely by the contact of our hands. That sort of unity is broken as soon as we release our grip, but the unity the Eucharist effects remains in place as long as we remain in the state of grace, in the friendship of God. If we focus on joining our hands at this point in the Mass, we tend to lose sight of the great mystery before us and instead focus on ourselves as the congregation, not the God with whom we are about to commune. (This communion with God also will result in our communion with each other, but the communion with God is primary, since it brings about the latter.)
We're not instructed to do it. It uses a gesture unique to the priest in the liturgy. It tends to focus on the congregation rather than the sacrifice of the Mass. Three strikes, Hand-Holding, and you're out.