Verb (used without object) : This teakettle whistles when it boils.    From Dictionary.com. 

Verb (used with object) : to whistle a tune. ,He whistled his dog over.    From Dictionary.com. 

Noun : a prolonged whistle of astonishment.    From Dictionary.com. 

At their best, The White Stripes' music was visceral, witty and milkman-whistleable all at the same time.    From Wordnik.com.  [The White Stripes: Detroit's rock heroes remembered] Reference

Dvorak's Quartet in G, Op. 106, doesn't get the air time his earlier quartets do, maybe because it doesn't leave you with a head full of whistleable tunes.    From Wordnik.com.  ['How Sweet the Sound' gospel competition; Calder Quartet; Left Bank Quartet] Reference

The opening "Europe Endless" (originally intended as the album's title too), features slightly more melodic singing than on previous albums, but more noticeably a synth melody which is captivating to the extent of almost being whistleable.    From Wordnik.com.  [Latest reviews @ Progarchives.com, the ultimate progressive rock music website] Reference