'The Final Page (Part 1)' - Season 8, Episode 11
With Christmas fast approaching, Barney tells Ted that he plans on proposing to Patrice, which leads Ted to debate whether or not to tell Robin. Meanwhile, Marshall and Lily run into an acquaintance from college.
Air Date: December 17th 2012.
Marshall: Before you murder us, you should know we have a child. He probably has 8 or 9. (refering to barney).