If I still remember "argentinian" (You know Rich, this questions of yours puts us emigrants in a difficult position, Martín is always watching us, ask poor Alex! <g>) other word you can use is "seguro...", and as Hilmar says, the tone is also important, it must show disbelief
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges
