how does Jem use stereotypes about gender to influence Scout?

When Scout refuses to retrieve the tire....

"'See there?' Jem was scowling triumphantly. 'Nothin' to it. I swear, Scout, sometimes you act so much like a girl it's mortifyin'.'

Jem's idea to play the Boo Radley game....

"Jem's head at times was transparent: he had thought that up to make me understand he wasn't afraid of Radleys in any shape or form, to contrast his own fearless heroism with my cowardice"