While you might not have "real" yarn and knitting needles, there are probably items in your home that will allow you to start learning to knit.
Many items can replace knitting needles. Pencils, wooden skewers, chop sticks, and even toothpicks are just a few of items that can be used as needles. Rubber bands can be used on the ends of the needles as a stopping device so that stitches do not fall off the far end of the needles.
Yarn is easily replaced by twine, string, small diameter rope, and even dental floss. In a hotel room, dental floss and tooth picks might be your only choice!