To make more sexually appealing or enticing.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "hot up" in a sentence
"At ye sides of the Arches are rings that you may hold by and so walke a little way, but ye springs bubbles up so fast and so strong and are so hot up against ye bottoms of ones feete, Especially in that they Call ye Kitching in the bath, which is a great Cross with seates in ye middle and many hot springs riseth there."