好久没改日记了,要不加你微信?好奇你能留做什么评论.
Maybe it's one of the messages that your friend leave? I don't think it's a joke or mockery, maybe it's a greeting or asking for opinions?
好久没改日记了:He or She or you haven't updated the diary in a long time.(like greeting words, or just state a fact)
要不加你微信?:Can I add your Wechat?(maybe he wants to contact you for further conmunication, also make friend with you )
好奇你能留做什么评论.:I’m curious that what will you write in comment. (waiting for your comments, maybe your words is interesting to him?)