The word whistleblower is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 26
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (87 words)
beerish, bellies, bellows, bestrew, bestrow, betoils, bewhore, billets, billows, blether, blister, blither, blowers, blowier, boilers, boletes, bolster, bolters, bothers, bowlers, bristle, bristol, brothel, elbower, erotise, estriol, herbist, herblet, herbose, heroise, heteros, holiest, hollers, hollies, holster, hostile, hostler, howlers, libeler, lobelet, lobster, loiters, lowlier, owliest, rebells, rebills, rebites, reboils, rellish, reswell, retells, retiles, retills, riblets, rillets, roselet, rowwise, sheller, shelter, sherbet, showier, slither, sorbite, sterile, stiller, sweller, swelter, swiller, tellers, tellies, thrills, tillers, toilers, tollers, trebles, trellis, trilobe, trowels, website, webtoes, whereto, whistle, wholist, willows, withers, wrestle, writhes