I am a bit scared of doing this as I don't know if it is rude or not. Another dc etiquette minefield to negotiate!
Background:DS bday party is next week and there are about four outstanding rsvps, all from boys- there are zillions of girls coming and far fewer boys. Invites went at end of term.
Do I
a)wait and see,
b)assume they're not coming,
c)assume they are coming
or d)just bite the bullet and ring up? Or get dh to ring up in the case of the mum I am a bit scared of? 
Is it rude to chase people up?