yī gū lu
with a rolling or twisting movement
in a single movement; in one breath
一
yī
one
骨
gū
used in 骨碌碌[gu1 lu4 lu4]
碌
lu
(bound form used in 忙碌[mang2 lu4], 勞碌|劳碌[lao2 lu4], 庸碌[yong1 lu4] etc)