If you have an identical twin, you've probably tried dressing alike so that people confound you with, or mistake you for, one another. You've also probably learned that, unfortunately, this trick doesn’t work on your mom.
The verb confound means both "to mistake" and "to confuse." If you decide to treat yourself to a delicious dessert, you might find yourself confounded by the overwhelming number of choices. If you end up ordering the chocolate cake but the waiter brings you chocolate mousse, the waiter has somehow confounded those two options. Another meaning you may come across in literature is "to damn," as in "Confound it! You are the most exasperating person on the planet."