Brallon is a ship of I Don't Know How But They Found Me's Dallon Weekes and Panic! At The Disco's Brendon Urie.

This ship became popularized by the frequent "stage gay" that happened during concerts, but it probably is not real because Brendon was(and still is) married to Sarah Urie(Orzechowski).

To recap; brallon is the "fictional" ship between Dallon James Weekes and Brendon Boyd Urie.