Why "Fenerbahce-Galatasaray" derby is named "el sikko"?

Barcelona-Real Madrid derby is named "el clasico"
Boca Juniors-RiverPlate derby is named "el superclassico"

what does "el sikko" mean? please translate it to me. i am with a Besiktas fan. he constantly laughs but doesnt explain the meaning..
Update: why is it funny? i want to know!!! also what does "ezikbahce" mean? and "6alatasaray" ? thx
5 answers 5