Gossip Girl stars Blake Lively and Leighton Meester have reportedly signed a deal to guest-star on U.S. TV show 30 Rock.

The actresses, who play spoiled students in their hit TV series, will feature in a Gossip Girl-inspired flashback sequence on 30 Rock during main character Liz Lemon's 20-year high school reunion, according to Ew.com.

But fans of the program will be in for a shock as the sequence will reveal geeky Lemon, who is played by the sitcom's creator Tina Fey, was actually a bullying teenager.