The X-Men were a well known hero team comprised of mutants.
When debating whether or not to go to a party, Peter Parker was pacing on the ceiling of his apartment and thought that the X-Men get to go to parties. Peter eventually left to fight Electro who attacked the same party.
The X-Men were neither seen nor heard, just a small reference.
The reference may have been to X-Men: Evolution, which was going on at the same time as the series.