刷飞机 means rapidly sending the
飞机 (airplane) virtual gift in a livestream. On
抖音,
快手, and
虎牙 the airplane is one of the higher-tier paid gifts (often hundreds to thousands of RMB each).
刷 here is the 'spam / send a stream of' verb — also seen in
刷火箭 (spam rockets, even pricier),
刷礼物 (spam gifts in general). Big spenders earn
榜一大哥 (top-donor) status.
