In most cases, it comes in the form of a predefined percentage of your initial deposit, usually 100% or higher.
http://forum.spolokmedikovke.sk/viewtopic.php?f=8&t=1062901
http://forums.shlock.co.uk/viewtopic.php?f=2&t=400709
https://br.gravatar.com/sitesdeapostasonlinedq
http://www.lada-xray.net/showthread.php?p=179550#post179550
https://google-pluft.nl/forums/viewtopic.php?pid=351017#p351017
http://www.horsecity.ru/phpBB3/viewtopic.php?f=22&t=492569
https://debate.socialism.nl/forum/showthread.php?tid=307816
http://aficionado.pl/showthread.php?617818-Gry-Hazardowe-Za-Pieniadze-Polskie-Kasyno-Online-Na-Pieniadze&p=668466
http://forum.spolokmedikovke.sk/viewtopic.php?f=5&t=1139220
http://aficionado.pl/showthread.php?541734-Jugar-Book-of-Ra-Online-ms-Casinos-Online-Con-Licencia-en-Argentina&p=587291
http://forum.spolokmedikovke.sk/viewtopic.php?f=23&t=1137201
http://www.lada-xray.net/showthread.php?p=278265#post278265
http://forum.spolokmedikovke.sk/viewtopic.php?f=11&t=1031150
http://forum.ruchkontroliwyborow.pl/index.php?topic=73041.new#new
https://ufr-2020.front5.picapo.net/forums/viewtopic.php?pid=528783
http://horsecity.ru/phpBB3/viewtopic.php?f=13&t=379555
https://talkingpoints.org/subx/showthread.php?tid=74853
https://debate.socialism.nl/forum/showthread.php?tid=245349
http://178.210.82.182/forum/delasupport/56478-jakie-s-sposoby-na-wygranie-wi-kszej-ilo-ci-pieni-dzy-kasyna-z-bonusem-na-start
http://forum.spolokmedikovke.sk/viewtopic.php?f=3&t=1100964