I'm half high, but what am I?

Question

See me once, with two joints, already half high
See me twice, as a part of the toast that the people will cry

See me once, at concerts, but not Bob Marley's
See me twice, aren't these some cheerful parties?

Hints will be added after 1 day, if needed. Have fun!

_{If you are not familiar with my See me once riddles, I recommend you first have a look at the latest riddles in this series:
#7, #8, #9, #10}

Answer 1

Are you:

Hip

See me once, with two joints, already half high

Hip joints, half way up your body.

See me twice, as a part of the toast that the people will cry

HipHip, Hooray!

See me once, at concerts, but not Bob Marley's

you see hip at HipHop concerts. But Bob Marley does Reggae

See me twice, aren't these some cheerful parties?

HipHip, Hooray! (this time, at a party)