Here's something you shouldn't ask on a construction site:
"What's that smell?"

The nail guns (which are cool) operate with little CO2 canisters. So when someone's been shooting, or nailing, a strange but distinctive smell fills the room.
hhhmm, there it goes again: nailing fills the room with a distinctive smell.

Anyway, when I asked, they smiled and I almost clarified, "No, it smells like gas," when I realized that's why they were smiling. I guess if you had gas you could mask it with the nail gun smell.

Speaking of what to say, I have encountered some Hispanic workers on the job. My Spanish is very weak, limited mostly to menu items, counting to 12, and whatever else I remember from Sesame Street, like agua. I suppose I could say "Beunos dios, amigo. Que pasa?" But I'm nervous they would try to talk to me more in Spanish.
Any advice? I need to put in my daughter's Spanish language CD-ROM I guess.