"mumbo jumbo"...Spot on!
Just listened the tapes my self. After IB crew says " we donīt need de-ice", someone is saying (British maybe?) "YOU DO"! Well done from him!!!
Hereīs the tape -> http://www.liveatc.net/archive.php and take KBOS-Delivery-Dec-02-2007-2300Z.mp3, right after mid point...
Everything is between 20:36 and 24:25