I also remember a Mississippi rhyme where you did a different move for the letters that spell M-I-S-S-I-S-S-I-P-P-I.

M- Jump into the square with both feet
I- Straddle the two elastics
S- Straddle one elastic
S- Straddle the other elastic
I- same as above
S- same as above
S- same as above
I- same as above
P- jump on both elastics
P- jump on both
I- same as above

* you basically do the same move for letters