Article in English: Scientists think that the way we respond to tickling has something to do with surprise and that we can control our response if we expect it. Think about it. Can you tickle yourself? Not very well because your body knows what is coming. The key to getting a good response may be surprise.  One good idea is to very lightly walk your fingers up and down your victim's sides. Or, you might try casually approaching the target. Put your arm around his shoulder or pull him into a hug. Then...tickle! Keep it up for a minute or so until you tire or he retaliates. As a slight alternative, go for a hug from behind and tickle his waist while you do so. Another strategy is the ambush attack. In this form, you will rely on complete and utter surprise. Wait for your target to round a corner, for example, and, when he appears, pounce! Make sure to use your momentary advantage to hit fast and hard, targeting the most vulnerable areas. Usually, one of the best and most accessible tickle spots will be his flanks around the rib cage. Go to town there. The armpits will also be exposed in a surprise strike. If your target is susceptible there, alternate between his underarms and flanks. If all goes well, your target should soon be laughing, tearing up, and rolling into a giddy ball on the ground. His defenses are down. You can now exploit his vulnerability and find other weak points.  Try the backs of the knees. This may only work in warm weather, if he is wearing shorts. The soles of the feet are often an excellent tickle spot and may not be exposed during normal activity. On the ground, though, you can definitely target them. Rely on your knowledge of the target. Recall his tickle spots and try to alternate from point to point rapidly. Moving in this manner will prevent him from mounting a defense. Consider tools that can help you reduce your quarry to a laughing ball of mirth. Different levels of softness or different textures should heighten the effect of the tickling.  A simple feather or a feather duster is one excellent...

Summary in Indonesian:
Gunakan seni kejutan. Incarlah sisi tubuh korban. Incar titik geli lain. Gunakan kuas, bulu, atau alat lain.