For a non-native speaker as myself, such a complex structure is really giving the creeps.
This book ought to have been going to have been being bound for six month since Tuesday.
What tense is it? How to understand it? Is it Future perfect continuous in the past?
The sentence was found in a comic strip on this Language Log website.
In a comment at that website, a user (Dan Lufkin) said, "Wow! This opens up new vistas in complex tenses. Chomsky's trifecta P This book has been being bound for six months can become Come next Tuesday, this book will be going to have been being bound…. And if something happens before Tuesday, you can add a little modality: This book ought to have been going to have being bound… A syntactic structure to be proud of, indeed."
in next post, he added, "Whoops! Make that This book ought to have been going to have been being bound … Dunno how I could have made such an elementary mistake."