What does Boxing Day have to do with boxing?
Old English sendan "send, send forth; throw, impel," from Proto-Germanic *sandijan (cf. Old Saxon sendian, Old Norse and Old Frisian senda, Middle Low German and Middle Dutch senden, Dutch zenden, German senden, Gothic sandjan), causative form of base *sinþan, denoting "go, journey" (source of Old English sið "way, journey," Old Norse sinn, Gothic sinþs "going, walk, time"), from PIE root *sent- "to head for, go" (cf. Lithuanian siusti "send;" see sense (n.)).
Also used in Old English of divine ordinance (e.g. godsend, from Old English sand "messenger, message," from Proto-Germanic *sandaz "that which is sent"). Slang sense of "to transport with emotion, delight" is recorded from 1932, in American English jazz slang.
[first sense fr or influenced by the course from New York City up the Hudson River to Sing Sing Prison at Ossining]
To arouse keen admiration, esp as an ecstatic response; excite; TURN someone ON: Bessie Smith really sent him (1932+ Jazz talk)
A mocking, teasing parody; lampoon; spoof: just another stupid soap send-up/ a relentless send-up of attitudes and gestures (1958+ fr British)