Blow air and breathe to mix up the sensation. You can breathe warm air or blow cooler air on wet skin. Always ends in shivers.
Like my grandma always said, “if you won’t eat it you shouldn’t stick your dick in it”.
I like to write out words with my tongue on his butt hole, like “I’m gonna bang you so good you’ll be moaning my name all week”, stuff like that! I’ve never met a guy who has figured it out, though.