[1] However, he is now best known for the popular Gift Grub segments which have featured on the Ian Dempsey Breakfast Show on Today FM since May 1999 which Rosenstock created alongside Paul McLoone, a radio presenter with Today FM and also frontman of the Northern Irish pop-punk/new-wave band, The Undertones which occurred in 1999 and when McLoone served as a producer for the Ian Dempsey Breakfast Show.

Gift Grub is a series of comic sketches, impersonations and parodies that have featured Rosenstock assuming the personae of Bertie Ahern, Ronan Keating, Colin Farrell and Roy Keane amongst many others; he also provides the manic voice of Right Price Tiles radio spokesperson "Daft Dave".

Rosenstock performed an impersonation of José Mourinho in a parody of a song from the musical Joseph and the Amazing Technicolor Dreamcoat.

Mourinho had heard the song and enjoyed the impersonation so much he asked Rosenstock to perform a private show for him and the Chelsea squad.

Between December 2007 and May 2009, Rosenstock worked on a puppet comedy series entitled Special 1 TV (originally I'm on Setanta Sports), which was presented as a parody weekly football talk show hosted by "José Mourinho".