Watch the Raga-ize Your Pentatonics online guitar lesson by Fareed Haque from Jazz Rock Workshop
North Indian or Hindustani Rhythmic singing is pretty complicated, as it is used to teach primarily percussion instruments such as the tabla. Each sound the tabla drum can make is assigned a syllable called a bol. For more info check out: Music of India
The South Indian or Carnatic Style is much simpler and useful for our purposes. Though the North Indian styles, particularly Punjabi folk music is super funky! South Indian rhythmic singing, called "Konakol," can be applied to any instrument and is something that even guitar players can use.
Ta for 1
Ta Ka for 1 2
Ta Ki Ta for 123
Ta Ka Di Mi or Ta Ka Ju Na for 1234
Ta Di Ge Na Ko for 5
After 5 start combining to make whatever mathematical grouping you need:
TaKiTa TaKiTa for 6
TakiTa TaKaDiME for 7
Try groups of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 against the beat and see what happens.