"Ponied up" is an informal expression meaning to pay or contribute money. Some synonyms for this phrase could be "forked over," "coughed up," or "chipped in." "Forked over" implies the act of handing over money, while "coughed up" suggests a reluctance to pay. "Chipped in" indicates that multiple people are contributing money towards a common goal. Other synonyms could include "paid up," "shelled out," and "put up." Regardless of the wording used, the meaning remains the same: to give money, often begrudgingly, for a specific purpose.