Souma is really susceptible to cracking up, and even memories will put him into laughing fits. But being self-conscious about this, he always tries to hide it. When he does this again at a clothing store his friend works at, the friend asks him why he does that, especially when it's so easy to tell anyway. Later, Shun also repeats the same sentiment...
Don't forget it again.
لا تنسَها ثانية
Wie konntest du das nicht merken?
Ne l’oublie plus.
Cerca di non scordartelo più.
Vê se não esquece de novo.
Смотри снова не забудь.