You are a sysadmin - whether you like it or not :flan_XD: It is not a sacrilegious title at all. Whereas I am a "professional sysadmin" (in the sense that I get paid for it at $dayjob) - I like cute shirts like this Cosplaying as a Sysadmin one.
Advice from a Dutchie, if someone looks at your apparel or makes a remark, say "heb ik iets van je aan ofzo?"
Quite literally translated: "am I wearing something that is yours" - it is often said as a joke and remark that they should mind their own business.