What does Boxing Day have to do with boxing?
1838 (n.), 1846 (v.), American English poker slang, apparently from Latin ante "before," from PIE *anti "facing opposite, near, in front of, before" (cf. Sanskrit antah "end, border, boundary," Hittite hanti "opposite," Greek anta, anten "opposite," anti "over against, opposite, before;" Old Lithuanian anta "on to;" Gothic anda "along;" Old English and- "against;" German ent- "along, against"), from root *ant- "front, forehead."
To contribute money one is responsible for or is expected to give: On April 15 we all ante up to Uncle Sam
[1800s+; fr the poker term for an initial contribution to the pot as a game begins]