My iud slipped and i had sec the night before and he had finished inside me could i be pregnant ?

Slipped ?: If you mean it fell out and is no longer in your uterus it would not work as intended.If it just moved some it probably would.Conception is a process that occurs up to 3 or so days after intercource with the conceptus moving into the uterus a a day or more later. The hormone coated IUD's have a different effect than the copper. But if either is gone I would not expect it to work.