before you take a shower, overload your mouth with toothpaste and brush your teeth as usual. Don't spit out at the sink, go to the shower, keep brushing till your mouth is filled with tooth paste and saliva. Now, don't spit it out to the ground of the bath tub. spit it into a wet wash rag. wipe your dick n balls with it and let it sit for atleast sixty seconds.
wash it off in normal bath routine and step outside fresh for your gfe session..
not only will DFK/LFK be tollerable but there's an extra sense of freshness down there that she'll enjoy a lot while going down.