I've had this too recently while standing on the sidewalk with a 8 yr old relative.
The joke was (keep in mind we were at the crossing while said car/person was about 2ft away)
He said; What do you call a black man in a red car.
I reply, shut up dont be rube.
He replies, regardless of what i said " a Malteser"
www.maltesers.co.uk
Ok now it dont seem to funny but in the given situation i was finding it very hard not to giggle.