Yeah it's like positive and negative sides of batteries
Elfin Girl + Elfin Girl = minor damage
Fat Man + Fat Man = massive damage
Elfin Girl + Fat Man = the bounce off.

Although I don't know what would happen if the fat man was running and the elfin girl was standing still. Probably some kind of steamroller effect. Further testing required.
( Kitty v1.0 desperately naive, Wed 3 Mar 2010, 12:17, 3 replies, latest was 16 years ago)

I don't know if I'm a sufficiently fat man for testing purposes
but I'd be happy to 'steamroller' any elfin girls you might have to hand
(LongJohnBaldry, Wed 3 Mar 2010, 12:20, Reply)

for greatest effect
have them both running, ideally indirectly crossing paths.

doesn't matter who - crashing while running into someone who is also running will cause instant change of direction (and most likely a faceplant or two)
(bamboozled Can hear you getting fatter, Wed 3 Mar 2010, 12:22, Reply)

You sat at the back in the science lessons, didn't you?

( Bartleby A dead man on vacation, Wed 3 Mar 2010, 12:23, Reply)

Science evades me entirely
As does maths. I'm a creative type, we don't need maths! Although it did take me ages to figure out how to work out the circumference of a circle so I could make a skirt recently.
( Kitty v1.0 desperately naive, Wed 3 Mar 2010, 12:30, Reply)

Poor attitude
I go to galleries, theatre and listen to music. You could at least watch Horizon once a week.

Bloody arty types.
( Bartleby A dead man on vacation, Wed 3 Mar 2010, 12:34, Reply)

I can't pretend to understand something
when I really don't.

I got As in all my science exams at school so my grasp must have been satisfactory. I just prefer language and the arts.

You've been to galleries and theatres, I've been to Eureka.
( Kitty v1.0 desperately naive, Wed 3 Mar 2010, 12:46, Reply)

That's alright then

( Bartleby A dead man on vacation, Wed 3 Mar 2010, 12:51, Reply)

We recycled paper
and made it into a keyring.

I haven't been there since I was a kid, mostly because I'm worried it'll be one of those places that's awesome when you're a naive child and ultimately crappy when you're a cynical adult.
( Kitty v1.0 desperately naive, Wed 3 Mar 2010, 12:53, Reply)