Diddling is a word that has multiple meanings; it can be used to describe cheating, swindling, fiddling, fooling around, or flirting. If you are looking for alternative words to convey these concepts, then there are plenty of synonyms that you can use. In the context of cheating or swindling, the word "defrauding" might be more fitting. For "fiddling", you could use "messing around" or "tampering with". If you want to describe someone acting in a foolish manner, you could say they were "goofing off" or "acting silly". Finally, if it's flirting that you want to talk about then "flirting", "courting" or "wooing" might be more suitable options.