2 – Her speech should not include anything that may provoke fitnah, such as jokes, soft speech or laughter, such as writing “hahahahaha” as mentioned in the question, or using emoticons to represent smiles, because that may lead to the one in whose heart is a disease being moved with desire, as in the verse (interpretation of the meaning):
“O wives of the Prophet! You are not like any other women. If you keep your duty (to Allaah), then be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery) should be moved with desire, but speak in an honourable manner”
[al-Ahzaab 33:32].