You shouldn't feel embarrassed about how you pronounce LaTeX. In the words of its creator Leslie Lamport:

> One of the hardest things about LaTeX is deciding how to pronounce it.This is also one of the few things I'm not going to tell you about LaTeX, since pronunciation is best determined by usage, not fiat. TeX is usually pronounced teck, making lah-teck, and lay-teck the logical choices; but language is not always logical, so lay-tecks is also possible.

See also http://tex.stackexchange.com/questions/17502/what-is-the-cor...