the NSIS word

[Yathosho]

just out of pure curiosity, how do you people pronounce NSIS?

1) N.S.I.S.
2) N-sis
3) Nis
4) (something else)

in the past i found it a bit difficult to talk about NSIS with other people, due to the nature of the "word". i ended up pronouncing it "nis". you?