5.1

5.1 refers to the state you are in when you become really loud after a drinking session. The 5.1 originates from the surround sound speaker system and hence you can hear the person from every angle.

1) Easy mate you on a 5.1
2) Turn it down bruv u reachin 5.1

5.1

A type of sound system.

Barlow: Five-point-one is *RIGHT*

5.1

theory of sorround sound for speakers. does not work with headphones.

1. ) "I bought an 5.1 surroundsound headset." "Well Bro that is bullshit. It does not work.!"

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.