1. Intent on disrupting your morning commute
2. Sleeps a lot (could be member of so-called "sleeper" cell)
3. Shows interest in bomb-making supplies such as acetone, sulphuric acid, or Kitty Litter
4. Goes out for hours late at night; on returning is not forthcoming about where he went, who he met, or what they were doing
5. Grows facial hair; foregos alcohol, tobacco, and coffee as prescribed in Koran