What word or phrase does your mother always say?
late 14c., "a musical sound, a succession of musical notes," unexplained variant of tone. Meaning "state of being in proper pitch" is from mid-15c.
"bring into a state of proper pitch," c.1500, from tune (n.). Non-musical meaning "to adjust an organ or receiver" is recorded from 1887. Verbal phrase tune in in reference to radio (later also TV) is recorded from 1913; figurative sense of "become aware" is recorded from 1926. Tune out "to eliminate radio reception" is recorded from 1908; figurative sense of "disregard, stop heeding" is from 1928. Related: Tuned; tuning.
[1970s+ Black; fr the similarity, recognized esp in black slang, between the odor of the vulva and that of fish or other seafood; perhaps somehow influenced by Tiny Tuna, homosexual slang for a sailor as a sex object]