My first son, who is 3 years old and a very ACTIVE boy, is now always doing all kind of gross little things. Examples: spitting everywhere, booger picking, erupting, pouring liquids at the table, among other eeewwww things. He is doing all this on  purpose and then he laughs. It is very disruptive, especially for the girls. How should I handle this type of behavior in little boys? Of course, I want him to have good manners but don't want him to become effeminate.

None of my daughters have exhibited this type of behavior so this is the first time for me.

I am, (you guessed it), mom. Dad is absent for the most part due to work.  

Sounds like he needs a good spanking. And no, it won't make him effeminate to expect decent behavior from a boy.

Whatever his crazy reason for this behavior, remember what Scripture says:
   
Proverbs 22:15
Folly is bound up in the heart of a child, and the rod of correction shall drive it away.

This is a perfect example of this. Doing stupid stuff. Don't try to reason with him, don't even mock him. Just consider it unacceptable and punish him every time he does it.

I have a bunch of girls and they all discover the "scream" at about age 1.5. But right now none of my older girls scream. That's because we always nip that in the bud: whenever they scream, they get a little snip to the cheek (whenever we're fast enough; for toddlers the punishment has to be near-instantaneous or they're going to wonder why you're snipping them!). That seems to take care of it.

For toddlers, you have to discipline like you'd train a dog or cat. Instant reaction.

I have a bunch of girls and they all discover the "scream" at about age 1.5.

Haha I know exactly what you are talking about. I wish I had knew better at the time. Now I have a 9 year old daughter (my oldest one) still screaming  :stare:

My first son, who is 3 years old and a very ACTIVE boy, is now always doing all kind of gross little things. Examples: spitting everywhere, booger picking, erupting, pouring liquids at the table, among other eeewwww things. He is doing all this on  purpose and then he laughs. It is very disruptive, especially for the girls. How should I handle this type of behavior in little boys? Of course, I want him to have good manners but don't want him to become effeminate.

None of my daughters have exhibited this type of behavior so this is the first time for me.

I am, (you guessed it), mom. Dad is absent for the most part due to work.  

It sounds like someone needs to learn some table manners.

Many years ago one of my fathers older sisters was having a party. It was boring and things were kind of dull. So my grandmother had my father (he was a little boy at the time) So my grandmother decided to liven up the party. She had him show them his pet turtle. They all screamed. She came in and 'scolded' him. He went into the kitchen and had a coke while the girls at the party had a little excitement and something to talk about.      

That sounds pointless, cruel and abusive Poche.

Maybe I do not understand well what it meant to do?