Rubbing himself against your leg....NO, don't let him do that. Here is an article on the subject .....I hope it helps.
Masturbation is quite common in young children. In most cases, it is considered a natural, normal behavior in children of all ages. Children often begin masturbating at around eighteen months of age. Masturbation tends to peak when children are between the ages of three and five. It then declines in frequency until puberty.
Many parents are surprised and/or shocked to find their children masturbating. Parents should keep in mind that masturbation generally causes no physical harm to their children. In most cases, problems result only when adults overreact.
For parents to deal with their children's masturbation they must know when it is normal and when it might indicate some underlying problem.
Why Children Masturbate
*Pleasure. Children learn very quickly that it feels good to masturbate.
*Self-soothing. For many children, masturbation reduces tension. These children may masturbate when they are upset, tired, bored, or feeling stress.
*Exploration. Many children will masturbate as part of the natural curiosity they have about their bodies.
What Parents Can Do
*Ignore it. Masturbation is, after all, a normal behavior for most children. Parents can best handle it by treating it matter-of-factly. Parents shouldn't try to get their children to stop masturbating by punishing, threatening or scolding. If they do, they run the risk of giving their children the idea that their genitals are bad and/or dirty.
*Remain calm. Parents should try not to overreact. They should also keep in mind that no physical harm will come to their children as a result of masturbation. If parents overreact, they may put fear into their children about their bodies.
*Don't be surprised. Masturbation among young children is very common, and quite normal.
When Children Masturbate in Public Places
Masturbation is something that should be done in private. Most young children, however, don't know the difference between public and private behaviors. In these cases, children must be taught. Parents should treat public masturbation as they would any other behavior that is not acceptable in public places, for example, nose picking. Here are some specific things that can be done to minimize masturbation in public places.
*Explain. If parents discover their children masturbating in a public place, they should tell their children that is something that should be done only in private, for example, in the children's bedroom or the bathroom. Parents should use words like, "It's all right to do that in the bathroom or the bedroom, but not in the grocery store or when other people are around." Parents should try not to criticize, nag, or punish their children. They should treat the behavior matter-of-factly.
*Offer alternatives. Parents should provide their children with something else to do with their hands while they are in public. They could also try to distract their children from masturbating by suggesting some other activity.
*Be consistent. If children, for example, masturbate while they are at day care, parents should work out a solution with their children's day care provider. It is important that the behavior be treated in the same way by parents and by other care providers.
When to Seek Help
On rare occasions, children's masturbation habits may be an indicator of other problems. Parents should consult their children's health care provider if:
*Children's masturbation interferes with their social interactions.
*Techniques to eliminate public masturbation have failed.
*Parents have any concerns about their children's well being.
*Parents feel that their children are possibly not masturbating, but scratching or rubbing the genital area because of discomfort. It may be possible that such children have an infection or a rash.
*Masturbation is constant.
Parents should keep in mind that in most cases, masturbation is a common, normal behavior in children. Very rarely is it an indicator of some other problem