Wikipedia
In Russian culture, khalyava / by khalyava is an untranslatable concept, similar to the concepts of "freebie" and " getting something for nothing", however with a different semantic field
Khalyava is a possibility to get something without particular effort. An distinction are that khalyava is something free one is not normally entitled to. It may be a result of luck. For comparison, if your friend gives you a ticket inviting you to go to me movies, it is not khalyava, if it is part of your normal relations, but if he gives you a ticket because your wife cannot go, then it is khalyava. Another possibility is that one gets something free in a way of dubious morality or legality, but not outright criminal.
The "something" you get is not necessarily something tangible; it may be a possibility to get something, e.g., to buy a rare book by a lucky occasion, i.e., "by khalyava".
A slightly different meaning for "khalyava" is an easy, low-effort job.
Both meanings are given in the Sergey Ozhegov's lexicographic dictionary, but absent in Vladimir Dahl's.
A person who is good at getting a khalyava is called khalyav nik or khalyavshchik, which may simply mean "a lucky man". However khalyava may come at the expense of others. In the first case it may be eating at restaurants at other's expence; in the second meaning this involves a skill to dump the hard part of the job on others. In this case "khalyavshchik" becomes pejorative and reasonably corresponds to " freeloader" of " free rider".
The low effortness of a job may be a result of sloppiness, and the latter concept is also within the semantic field of the term "khalyava" and the derived adjective.