Yuh Yuh Yuhhhhh was created in a mashup that was performed/recorded by Why Don't We. The mashup consisted of
Gucci Gang and
Ten Million. Yuh Yuh Yuhhhhh was said by Corbyn
Matthew Besson, 1/5 of Why Don't We. Yuh Yuh Yuhhhhh means 'yeah, yeah, yeahhhhh.'
This is how it was preformed:
Gucci Gang,
Gucci Gang, Gucci Gang, Gucci Gang
Corbyn: Yuh Yuh Yuhhhhh
Gucci Gang, Gucci Gang, Gucci Gang, Gucci Gang.
(just a snippet of their mashup rest can be found on their
Instagram, @whydontwemusic )