Like this conversation with Makarov during a meeting with the members of the Fairy Tail Guild. While Mararov was at it, Natsu went to the toilet, and somehow, the conversation led to an unholy discussion about Dark Guilds. Makarov was having a cough. Each time he turns to the left to converse with Happy, his cough would subside. But every time he turned towards Natsu on his right, he would cough profusely. Think Natsu is not good for blood pressure.