Msg 28, "ricini"
Ricini might be funny, if not so ridiculous and somewhat dangerous.
If you want to mix saliva with anything, especially something as unpleasant tasting (for most of us) as castor oil, you spit into a container, pour in the castor oil and...watch them not mix.
Saliva doesn't digest castor oil. Saliva digests starch. You can demonstrate this by placing a peice of regular (not sweet) bread into your mouth and sucking on it. Eventually it will turn sweet. That is the starch-splitting enzyme, ptalin in saliva, splitting the tasteless sugar polymer (starch) from the bread into simple (sweet) sugar.
To split (digest) fat, in the body, you need the enzyme lipase. Lipase is produced in the small intestine. But lipase can't get at the fat without help. That is the purpose of bile. Bile, sent into the small intestine via the bile ducts from the gall bladder, makes the fat able to connect with water, which carries the lipase. (Btw, it is the alkaline bile that dissolves the enteric coating from bisacodyl laxative pills, releasing the bisacodyl to do it's work.)
So, saliva, having neither an emulsifier, nor a fat-splitter, cannot make castor oil into a laxative (ricinoleic acid). If it did, the laxative would work in the stomach, causing vomiting, before getting to the bowel, to produce it's laxative effect.