Is there some kind of initiation in Buddhism similar to christening or somthn in Christianity?

I would say, if you're looking for a formal ritual similar to the baptism of Christianity, it might be this:

A person "formally" enters a Buddhist path by saying: "I take refuge in the Buddha, I take refuge in the Dharma, I take refuge in the Sangha". Usually this would be said in the presence of the Sangha (fellow practitioners). It might be said formally in front of a Buddhist leader three times in front of a group of people witnessing it in a ceremony, or it might just be something done informally with one other person.

But don't be misled: it's not nearly as important to Buddhists to "say" this "correctly" as baptism is as necessary to Christian doctrine. Buddhism is not dependent on doctrine or rigid dogma like that.

Just adding on to "bentthebookseller's" answer, you can make a formal declaration that you will commit to practice with a sangha. What's really more important is that you practice what the Buddha taught so that you can experience it for yourself. I think the term is "ehi-passika" which means "come and see [for yourself]."

I guess so but it's not that important. Study buddhism for its insight.

Yeah you have to knock of a few hershy bars and a coke in the nude.