Foot play doesn't have to involve just licking and sucking, but if your partner has a penis, you can give them a foot job by stroking the shaft the way you would with your hands. If your partner has a vulva, you can rub their vulva and stimulate the clitoris with your toes. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.