The phrasing here is important so don't get cute or snarky!
"I am invoking my right to an attorney. I am invoking my 5th Amendment right to remain silent."
If you phrase it any other way, many courts have stated it doesn't cou.t.
here's a dumb question from a foreigner: would it make sense to just carry a bunch of laminated cards printed with that sentence and just hand them to the cop?
"I want a lawyer!" I want a pony. Since we're just stating things we desire and not invoking rights.
"I'm staying silent." If you say so, but you haven't invoked your right to remain silent so the cops can keep questioning you.
Just staying silent doesn't count either. You MUST invoke your right.