"Guess that's one way to get out of math homework Who needs calculators when you've got pigeons and projectile vomit? On the bright side, your tardiness is officially validated as 'avian-related' #PigeonProblems #TardyWithFlair"
That scales much worse of course.
Drivechain is a pretty good solution if we can get it, other possible solutions must involve trust, but in a decentralized way.