"Waving your arms" 就是挥舞你的胳膊的意思。
这个短语来源于英语中的动词 "wave"，意思是挥动、摆动。而 "arm" 意思是胳膊。
例句：
The crowd was cheering and waving their arms.（人群欢呼着，挥舞着他们的胳膊。）
She waved her arms frantically, trying to get the pfeguard's attention.（她疯狂地挥舞着胳膊，试图引起救生员的注意。）
He was waving his arms around, making wild gestures.（他挥舞着胳膊，做出疯狂的手势。）