'Ttak-bam Kings' Lee Seung Gi and SHINee's Onew recently had a battle on SBS's "Strong Heart"! Ttak-bam is the act of flicking your fingers to hit someone, oftentimes on the forehead. It doesn't sound all that impressive, but when done right, it can hurt like no other. Onew had previously shown off his strength and skills on programs like KBS's "Night Star" and "Happy Together". Lee Seung Gi had done the same many times through "1 Night 2 Days". They've both made many celebrities feel a whole lot of pain, and have been very proud of it. This time around, they battled it out on "Strong Heart" to determine the true 'King of Ttak-bam'. After going around the room asking castmates for their votes, the boys then decided to test their skills against each other. Although Luna tried once again to intervene and warn everyone of Onew's strength, Lee Seung Gi and Kang Ho Dong decided to go ahead. In the end, both the audience and castmates became fairly terrified by the strength of the contestants' fingers, but the winner was determined to be... Onew! Source: MyDaily via Nate