And he revealed that plain clothes officers look out for anyone who turns tail
once they see the scanner.
As he turns tail
to head home he gets a call to bring in computer hacker Matt Farrell (Justin Long) but when McClane turns up at the tech-head's house they are caught in a full-on gun battle because someone wants Farrell deleted.
This is the point at which the tap on the shoulder causes the Dame to turn round - whereupon the terrified intruder turns tail
. At least, that's what it always used to be - but just lately the laughs have seemed to depend upon a good show of sheer terror from the Dame as she gallops away, which is not nearly as funny.