Islamic Interpretation of Dreams (Ibn-i Sirin):
(Underpants; Underwear) If one discovers some wetness in his underpants in a dream, it means that his wife is pregnant.
If one defecates in his underpants in a dream, it means a fight with his wife after which he will pay her something he owes her, or it could mean a fight that will end in divorce.
If one wears his underpants inside-out in his dream, it means that he indulges in the loathsome and forbidden act of anal intercourse with his wife.
If one sees himself wearing his underpants without the underwear shirt in a dream, it means poverty. Wearing fancy underpants in a dream means travels, or financial growth. Wearing new underpants in a dream means protecting one’s chastity. Giving away one’s old underpants in a dream means relief from difficulties.
(Also see Underwear; Pants)