It generally depends on the situation. Laughter can have many different reasons behind it - they think something is genuinely funny, nervousness, anxiety and it also serves to relive stress and cope with other feelings, such as fear or anger. Toddlers are at a very critical age emotionally and are just learning how do deal with their feelings and how to interpret other's reactions. Try to put yourself in the child's shoes and also examine the situation: How do you react when the child laughs and could that be contributing? Toddlers will usually do what works for them the easiest. Perhaps it's time to take a new approach to discipline...one the child can better understand and cause you less frustration.