extra 2 inches

When you get an erection and your dick gets longer

OMG honey you just got an extra 2 inches

5.1 inches

The average penis size on the world according to the first google result

Also see:
12.9 cm
1.5 credit cards
0.5 bycicle tires
2 Nobel prizes

Dude I heard Robert's penis is 5.1 inches
Really! Mine's only 2......Nobel prizes... O-of course.