Debecker discusses the approaches used by perpetrators of violence on women or children. They include charm, promises, excessive claims of familiarity/we're in the same boat, etc (I think there are 7 or 8 total).
So you're out with your kid and this guy comes up and offers to take your kid over to the arcade for a few minutes to play with his kid. His kid is the same age as your kid, they'd get along great, it would give you a chance to finish your shopping without being hassled, etc.
He ignores your first refusal and just keeps talking about how great his kid is (alarm #1)
He stops talking to you and starts talking directly to your kid (alarm #2)
He says to you "oh, you're not one of those over-protective parents right - so it won't be a problem?" (alarm #3)
All the time he ignores your polite refusals. Which means it is time (past time) to make a firm refusal and get away from him - he's obviously got an agenda.
The book is a good read, I highly recommend it.
But basically he's saying that if someone gives you the creeps - tell them no, whatever the situation. Don't accept the offer. If they're a good person they might get annoyed but they'll respect your decision. If they've got an agenda they'll keep pushing until they get what they want - one way or another.
So a nice guy might get a little pissed that you didn't let him help you carry your groceries to your car, but a bad guy is going to keep following you, bugging you, tagging along, doing whatever he can to cloud your judgment and limit your options until he gets what he wants.
And I say "guy" because Mr. DeBecker asserts in each and every one of his books that the vast majority of violent crimes and especially predatory crimes against children are carried out by men. Doesn't mean there aren't exceptions but those exceptions are less than 3% of the perpetrators.
Did you show compassion today?