Hilchos Ishus 6:6
Let’s say that a man tells a woman, “If you don’t give me 200 zuz, then you aren’t consecrated to me, but if you do give them to me, then you are consecrated to me through this dinar,” after which he gives her the dinar. In such a case, the condition is immaterial because the ramification of not fulfilling the condition was stated before the ramification of fulfilling it. In such a case, marriage is immediately effected and she need not give him anything.
Hilchos Ishus 6:7
Similarly, let’s say that a man tells a woman that she is consecrated to him through a dinar on the condition that she ascends to the heavens or descends to the depths, but that if she doesn’t do so, then she is not consecrated, after which he gives her the dinar. Such a condition is immaterial and marriage is immediately effected. It is obvious that she cannot fulfill this condition and he must therefore be joking.