Upsilon is pronounced “oo”. Make that sound and relax your mouth at the end and you get “oo” + “eye”, which is very close to “wye”. Or say, “Not the usual I, b

Upsilon is pronounced “oo”. Make that sound and relax your mouth at the end and you get “oo” + “eye”, which is very close to “wye”. Or say, “Not the usual I, but the ooh I” enough times and the end sounds like Y. (Warning: I am not a linguist.)