service · the act of giving away something or doing something for free, as a gift or free service for someone; on the house · a free add-on to a product or service, generally a substantive and desirable one; lagniappe
köken: Borrowed from English service. Although possibly used differently to the modern meaning, it is attested to have been used by Koreans in 1942 during the Japanese Occupation of Korea.
to top it off (of something negative), to make matters worse
köken: till (“to”) + råga (frozen archaic genitive of råge from when till governed the genitive) + på (“on”) + allt (“everything”), "as a heaping [the heap of something heaped, like a heaped teaspoon] on everything"