Galician Ashkenazi pronunciation of the Hebrew Sheh-hechiyanu, which is the name of a thanksgiving benediction that is recited to mark special events.  One thanks God, “…Who gave me life, and maintained me, and brought me to this moment.”  The blessing is said on momentous personal occasions, such as at one’s wedding, or child’s circumcision; at more prosaic moments, such as the first time you eat a fruit that has come into season; at the beginning of a holiday; and when you get to do a commandment (mitzva) for the first time.  The use of the word here is ironic: this is the first time in their lives Mechel and his companions are violating a holy day, and they are saying a sheh-hechiyanu on a sin, not a mitzvah.