Etymology
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fillip (v.)
mid-15c., philippen "to flip something with the fingers, snap the fingers," possibly of imitative origin. As a noun, from 1520s, fyllippe.
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flip (v.)

1590s "to fillip, to toss with the thumb," imitative, or perhaps a thinned form of flap, or else a contraction of fillip (q.v.), which also is held to be imitative. Meaning "toss as though with the thumb" is from 1610s. Meaning "to flip a coin" (to decide something) is by 1879. Sense of "get excited" is first recorded 1950; flip (one's) lid "lose one's head, go wild" is from 1949, American English; variant flip (one's) wig attested by 1952, but the image turns up earlier in popular record reviews ["Talking Boogie. Not quite as wig-flipping as reverse side--but a wig-flipper" Billboard, Sept. 17, 1949]. Related: Flipped. Flipping (adj.) as euphemism for fucking is British slang first recorded 1911 in D.H. Lawrence. Flip side (of a gramophone record) is by 1949.

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snitch (n.)
"informer," 1785, probably from underworld slang meaning "the nose" (1700), which apparently developed from an earlier meaning "fillip on the nose" (1670s). Snitcher in same sense is from 1827.
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