If you're on a laptop posting from, say, a Starbucks or something of that sort, YOU cannot be traced. Only the location.....In other words, the IP address would come back to the Starbucks location, that is it.
Administrators of such forums CANNOT pinpoint an exact address and/or identity of a poster. They can narrow down location and the IP service provider. An IP provider would not turn over the identity of an IP address to a forum just for the hell of it. If there were threats or other such reasons for pursuing an identity, it would have to be done so by a legal means.