Better than Average Cory - S6-E5
Continuity mistake: When Rachel starts writing down that she is choking, she knocks a cup of water off the counter. After she spits out the hot dog she was choking on, the cup has reappeared on the counter. (00:06:38 - 00:07:00)
Answer: Topanga's middle name is never specified. Considering her sister's name is Nebula Stop-the-war Lawrence, Topanga's is probably something equally unusual.