This is based on a television advertisement.
Semtex is an 'inexpensive' Czechoslovakian plastic explosive.
In the printed lyrics for "What God Wants, Part I", some versions of ATD have "The alien prophet cried" written; "prophet cried" is what's sung.
"Each man has his price Bob
and yours was pretty low"
Waters explains this line..."When we recorded the album I would sometimes rehearse vocal takes by impersonating Bob Dylan. That line originally read 'Each man has his price my friends...' so make of that what you will. As a joke I sung Bob instead and Pat insisted that we leave it in. So although it was unintentional I'm happy that it's there for Bob Ezrin. I hope he appreciates it."