Sayings 'a dime a dozen' & 'pull someone's leg'

[undeddy]

Are those idioms common? I mean, are they worth learning them? :)

[amigos4]

Are those idioms common? I mean, are they worth learning them? :)

These idioms are commonly used in the United States. You should be aware of their meanings because you will hear them when speaking with a native speaker from North America.

[Trance Freak]

These idioms are commonly used in the United States. You should be aware of their meanings because you will hear them when speaking with a native speaker from North America.

thought it was used by canadians as well + one can hear it a lot in action movies, u no as in prison sentence or 10 bucks ?

[undeddy]

Are they perceived as casual and informal phrases?

[amigos4]

Are they perceived as casual and informal phrases?

Yes! Idioms are reflective of regional speech or dialect and can be used in casual and informal conversations and correspondence.