jonas sidecar means in slang: A jonas sidecar, which is technically a sexual act that keeps everyone’s virginity promises, is called the jonas. A guy promises to ring-finger a girl with his left hand and then masturbates using their right hand. Sidecarring the girl, the guy climbs onto her bed. After the act has been completed, the guy offers the girl gas money. Are you willing to trade a 5 and a 20 for change? (in Slang Dictionary, added by Killian Harrington)