for the sake of discussion this is every potential joker synergy i have found so that we could go straight to balance problems/discussion instead of needing to rehash potential uses
General - in most situations you can guarantee you won't win the round until the specific hand you want to. Allowing you to fish for utility cards or farm econ/scaling jokers in cases where you win rounds too fast.
Food Jokers - allows you to save almost every food joker from degrading, either partially or completely. notably, Turtle Bean becomes a unconditional +5 hand size and Ramen becomes a unconditional 2x mult. the fridge depiction is meant to hint to this being one of its direct synergies.
Ride the Bus, Green Joker, Obelisk - allows you to debuff it when activating its down sides to get only the upside activations.
Ancient Joker, Castle, The Idol, Mail-In Rebate - allows you to stop rerolls if you debuff it on final hand played. currently only Mail-In Rebate works this way, i would imagine this joker would make either all of these or none of these work for consistency.
Campfire, Hit the Road - stops scaling from being reset if debuffed on final hand.
Vampire, Midas Mask - allows you to play enhanced cards if you're ok not having its effect that hand.
Ceremonial Dagger - in very rare cases where you can't put dagger all the way to the right when it activates, this can save it from activating.
Loyalty Card - allows you to save its activation hand for when you need it most. currently does not work this way because of a bug (already reported by someone else.)
Paredolia - can disable it without needing to be sold, potentially saving a run with a innoportuned The Plant.
Madness - allows you to decide when madness has scaled enough by making it no longer destroy jokers.
Oops all 6s - allows you to selectively decide when you should be lucky.
Stuntman - avoid -2 hand size unless you specifically play a hand with stuntman active