Animals
A person who prefers his own company and does not like socialising.
Lone wolf
Smart cookie
Know-it-all
A very talkative person
A person who is particularly interested in technology and studies a lot
Nerd
A person who has very little emotions
Cold fish
Full of beans
Pain in the neck
Someone who is not able to keep a secret
Big mouth
A relaxed person who doesn't get stressed or upset easily
Laid-back
Someone who likes to attend parties often
Party animal
A person who spends time sitting in front of TV doing nothing
Couch potato
A people person
Someone who talks too much
Blabbermouth
Someone who is practical and close to reality, who accepts other people as equals
Down-to-earth
Someone who wakes up before the usual time
Early bird
As cool as cucumber
Cheapskate
A person who constantly complains about everything
Moaner
Someone who always wants to do something for others so they like him/her
People pleaser
Someone who's always willing to do something
Eager beaver
Play truant
A person who seems to be stupid
Dipstick
A person who always advises people but does nothing to fulfill them
An armchair critic
Have a screw loose