4 .
You are about to be introduced to another friend-of-a-friend: this time, a lively-mannered man who is clearly full of interest and experience ('the life and soul of the party'). Your friend tells you quietly, just beforehand, ' ... But do be a little careful; sometimes he can't keep his hands to himself'.
What are you supposed to be careful of, as you go to meet him?
He tends to steal things (picking pockets, etc.) when the chance presents itself.
He is sexually predatory, and will try and touch (probably, young and/or female) people in uncomfortable ways and places under the pretence of being friendly.
He will be likely to move too close to you for comfort, 'invading your personal space', fingering your clothing / jewellery etc., which you may well find disconcerting.
He has a very strong, firm (and perhaps, long) handshake ... don't let that take you by surprise!
Answer 1 is occasionally used, though the feet of a baby less than one year old ('this time next year') are unlikely to be 'pattering' ~ as it takes longer than that for a baby to learn to stand, walk and then run; but the sense is reasonably clear.
Answer 2 is rather solemn but does make sound medical sense; Answer 4 is very casual!