First of all, remember firmly: no jokes about the life or health of her family and friends! Alas, there have been cases where seemingly normal, intelligent guy mournful voice said to his girlfriend something like this: "Lena, don't worry. Your mother was hit by a car!" And then he himself felt resentment: not only is this bitch Lenka, recovering himself, cursed it, tried to beat, so also ran out of sight!
Will refrain from the temptation to demonstrate wit, appeared before the parents of his girlfriend with the words: "Hello! As an honest man, I agree to accept the child and marry Nadya". Believe me, you brilliantly demonstrate the very different qualities which will hardly appeal to both Nadya and her family.
From jokes about real or imaginary flaws in the appearance, especially some of the physiological peculiarities of the female body, should also resolutely refuse. Remember: women are very sensitive about everything that is connected with visual appeal.
A little thing that the guy didn't even pay attention, can cause severe suffering of depression in girls. Well, "critical days" many girls, especially in adolescence, occur very hard, causing them a lot of physical and mental discomfort, so any joke about this can lead to anger. And, honestly, the girl is blamed for not!
So remember a wise old rule: "Everything in moderation". A joke should not hurt, especially cause moral injury. The drawing should be such that after it, like genuinely laugh for everyone – including the object. There will help you a sense of proportion and taste. Well, of course, love the girl!