"polom" is a greeting, usually used in our Matrix channel (formerly we used IRC). It's a reference to what was saying Tom Bombadil when walking in the forest "Polom polom it's Tom Bombadil" or something like that from a J.R.R. Tolkien book.
Given its use, some community members even traveled to a village called Polom during TikiFestCEST. See pics
Polom Tiki.org! A "greeting card" from the TikiFest