I think he thinks it's funny how NOT original Volstagg is (and that it's darkly funny that things haven't really changed). Because his reaction to Sif vs Volstagg is actually very different. -- I feel bad for Loki.
(gif) Please note: Sif in the background. Her face is priceless. Apparently, one does not simply punch Loki. Unless you are Jane Foster.>> Sif: I might like her!««« lol loved<><><>Finally someone mentions Sif's face!