ice missile

(名詞) 冰飛彈 - 從行駛中車輛的車頂飛出的大冰塊。

In another move, many motorists are unaware of a new law that will require drivers and truckers to remove the ice and snow from the roofs of their vehicles in order to avoid "ice missiles" that can come flying off their roofs.
—Christopher Keating, "Rail Fares, Minimum Wage Going Up Wednesday," The Hartford Courant, December 30, 2013

"I can't tell you how many times I saw what I call a 'slow-motion nightmare'" on the highway, said House Minority Leader Lawrence F. Cafero, who first spearheaded the effort to ground "ice missiles" in 2001. "You can't do anything. You're surrounded by traffic. You're just watching it happen."
—Keith M. Phaneuf, "First storm of 2014 tests CT's new 'flying ice' ban," Connecticut Mirror, January 3, 2014