When you say “Hello”, they answer ”World”.
They use nested parentheses in normal writing (at least I do (sometimes)).
They are wearing socks (and sandals).
Ask them what languages they know.
You can tell the programmer by the way he names numerous langauges but forgets to include ‘English’.
If you ask them a question there is a pause as they break out of the for loop.
If you ask them whether they use Mac or Windows, the answer is ”Usually not.”