Hong-Pong is the 15th level in Serious Sam 2.
After defeating Zum Zum, Serious Sam is sent to ChiFang to retrieve the next Medallion piece from Prince Chan. Soon after he arrives, he is attacked by Mental's forces. It seems that Prince Chan has aligned himself with Mental, making things more difficult for Sam. However, Sam manages to fight through the outskirts of the city, and eventually reaches Prince Chan's amusement park.
1. As soon as you get past the first gate, look to your right and start walking. Past the building with the Uzi in it is a barrel on an overlook. Position yourself so that you can bounce a RB-45 Hand Grenade from the roof above the barrel so that it lands next to the barrel (hint: get very close to the overlook, then toss a grenade). When the grenade blows up, it will destroy the barrel, which will release a Serious Bomb. Pick the Bomb up.
2. Go back to where you entered the second area from the first gate. Now, go forward until you see a path on the left. Go down that path to it's end, then look left. You'll see a dead chicken. Walk up to the chicken to register the secret.