It doesn't need to make sense just post anything here, to help out with this achievement, if you need the 100 post achievement, and its for fun while doing it
And don't forget to ping folks to have them catch up..

...is this allowed?

I haven't found anything against it? I mean if folks can rent out stuff to others and help out with those achievements I really don't see much difference.

Well, the difference is that posting for no reason other than to rack up more forum posts is considered spam. Just try joining in the conversation others are having in threads that are of interest to you and you will have your forum posts in no time. :) Because of that I will be locking this though.