What's going on?
I suppose you are referring to posts like this and this.
Those really are weird, but it might be possible to make some sense out of them by looking at the context.. although very vaguely.. Maybe saying "they are so cool" at the simple machines forum thread refers to people behind the SMF project being very cool? And the "impossible is nothing" on the IRC announcement could be an impressed thought regarding the way people come together on IRC to discuss anything.. OK I might be stretching. 
Sure is weird, but there are no links, nothing to indicate anything unclean besides the weird post, so it is basically not really harmful, and those threads are inactive anyway.
The only issue could be that this, if it happens too often, could annoy others a bit, in which case I would condone removing them. But right now I think just leaving as is, but watching out for more, would be ok. If anyone has a suggestion on that, please post.
Thanks




Apart from our two spammers "milf" and "appletv" who just won't stop no matter how often we delete their posts (and the latter is a liar, too: his product is NOT open source), some other weird useless posts appeared. They are short, say nothing about the thread they are replies to, and just make me wonder what to do with them since they are strictly not spam. One contained only a bad word, so I edited it, another was a double post with a long time between the posts (second one deleted) and a third one was simply useless. What is whoever is posting these trying to do? Figure out the forum rules by trying breaking common ones?
Very odd.
If you run a mile, does that make you own the road?