We have a 9 yr old gelding who over all is very calm.  He has always put his ears back when we bring his feed and hay, never done anything else, just pinned those ears.

Now he has started "lipping" at strangers and especially smaller children.  He doesn't do this to us.  The other day he started doing it to our neighbor while she was stading outside his stall.  I smacked his shoulder and then he showed his teeth so I really wacked him good on the shoulder.  After that he was fine with her.  I should say this did not happen during feeding time.

Any suggestions on how to put a stop to this?  Especially with smaller children.  I think his problem with them is that they are quick and darting around, but that is only a guess.  Of course we are right there with him and the children, but I just don't care for his attitude.

I just went through this with a new gelding that I got about a year ago.  I did the tac thing and he new exactly what that was he would lip the tac's around my hand on a band.  Smart little rascal. Smacking didn't help he just thought it was a game.  He has always been a mouthy horse. Just playing with everything.  What worked for me was something I picked up from John Lyons. One day he nipped at me while I was picking his feet, I was moving from one holf to the another, mistake, I gave him the 3 seconds of death treatment. I was hollering, jumping up and down throwing my hands in the air flalling around, I just lost it so to speak, and never touched him for 3 seconds. He about had a heart attack and backed away quickly. After 3 seconds I went on like nothing was wrong and continued to do what I was doing. He has been so much better since then.  It only took one time but I will beat I have to do it again one day just to remind him. I told one of my horsey friends this and he about died laughing so hard.  Come to think of it, it was funny as all.

Since then I have just played with his nuzzle for a while before I do anything with him. He seems to just want that attention and he will try to nip to get it.

Spooler has right answer for you.  

I too, have used this method and it works.   This method is used for any of the nastier behaviors that a horse can pick-up.  There is no hitting or slapping or needle tricks involved.  It is totally a training of the horse's mind. 

No offense to anyone...... but, the needle and tack in the hand trick can often times end up with the object stuck in you instead of the horse.  Also a good way to inject germs/bacteria into your horse or yourself.  In my humble opinion the Johns Lyon method works better and no one gets hurt.   Good Luck.

I've had horses fixed by both methods, 3 seconds of terror and a full on punch in the smacker.  Both horses started with "cute" little nibbles that turned malicious.

The horse I punched in the mouth was a knee jerk reaction and unplanned.  I bent over in front of him and he bit my booty.  I snapped up and came around swinging.  I cut his lip and my knuckles on the one impact.  He never lipped, nibbled or licked me after that.  I don't know who was more shocked after contact him or me.  Note:  I don't recommend punching your horse in the mouth, it can make them head-shy and bit-shy...but my horse suffered neither after the incident.

farmbabe, I couldn't rub his muzzle afterwards because I needed medical attention.  I don't think putting your hands near their mouth is good practice anyways.  I'm not saying don't touch their lips but don't play with them...it sends mixed signals.

When you halter break a calf you don't scratch their heads, it teaches them to head-but and invade your personal space.

I just got my gelding back after 3 years of being leased out. I know you take chances when you do this, and fortunately he came back healthy and happy, but oh-so-mouthy! He's not grumpy or trying to intimidate, he's quite people oriented.

When we sent him to these people, we asked please, no hand feeding of treats. We knew he was somewhat mouthy, in a cute kind of way. He was notorious for untieing shoelaces and removing things from tack boxes etc. But then he started grabbing onto clothing and once latched onto my daughters coat and scared her. We then started to discourage this behavior and asked the people leasing him to do the same.

 I know they followed that rule in the beginning, but apparently, over time, started hand feeding him treats and allowed him to lip and lick. I know it's hard to resist, but ultimately, it's dangerous. And we are having to start all over again. For the time being, it's a firm "NO" and a flick of the fingers on the lips. and absolutely no hand feeding of treats - He gets treats, but they go in a bucket.

We also need to work on that "space" issue. He'd like to crawl right into your pocket, but that's kind of hard for a 1000# animal to do!

It's interesting to note that these people did a lot of the Parelli stuff with this gelding, but I believe it kind of backfired, in that they weren't consistent and firm enough. Because he is such a lover, not at all aggressive. But again, he's a 1000# puppy and that can be dangerous.