A "bet bonus" is a type of reward or extra benefit that you receive when you place a bet. It can include things like free bets, extra money to bet with, or improved odds on your bets. Full definition
If you've claimed a free bet bonus before then you'll find that this one works similar to other offers but does have a bit of a twist. (cheekypunter.com)
If you need to sign up with them, take advantage of their # 20 free bet bonus as welcome offer. (football-bookmakers.com)
The betting community certainly agrees with odds of 9/2 for the switch and a plethora of recent free bet bonus offers being made available for the festive holidays. (footballtarget.com)