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blow on (something)
To expel air onto something. Hey, that coffee's piping hot, so blow on it before you drink it. The vent has been blowing on me all morning—I'm freezing! I blew on the dice for good luck.
blow on something
to force air across something especially with a puff of breath. Jill blew on the hot soup. Blow on the fire to make it burn hotter.