Błędnie: The audience was so anxious to see the band, that they whistled the supporting group away. Poprawnie: The audience was so anxious to see the band, that they booed the supporting group.
"Boo" oznacza 'wygwizdywać (kogoś, np. ze sceny)'. "Whistle away" to kalka językowa- taki phrasal verb nie istnieje.