Como dizer "vaca de presépio ou bobo da corte" em inglês

I've never heard of a "vaca de presépio" (lit., nativity scene cow). What does onesuch cow really do, does it stand around all day ogling younger Jesus while He smiles angelically at all around him?

Eu já ouvi essa expressão 'vaca de presépio' e ser isso significa ser bobo, manipulado, que os outros fazem de fantoche, etc.. Ou seja, parado, como a tal nativity scene cow ^^ P.S. pelo menos aqui por MG/SP (meu 'habitat' kkkk) essa expressão é conhecida^^

Maybe "Court Jester" but it seems not to be used in the way you are trying to use it.

Ditados e Expressões variam de lugar para lugar em qualquer língua, por isso eles servem mais como diversão ou aprendizado de compreensão!

Vaca de presépio - one that usually jumps on the bandwagon, someone that acts "Maria vai com as outras". It´s becoming an outdate expression these days, it was used in Rio some decades ago...

Bobo da corte - generally is said pejoratively "he is a fool" about someone that "is making a fool of himself" (generally by saying something improper, lying through his nose/being unfair/not being reasonable, etc). It is usually said of a person that is a "suck up", someone that doesn´t criticizes their higher-ups (bosses, teachers, higher in rank, etc), and seeks attention by cumplimenting.

It can be said of a whining guy as well, when he complains without a reason, people say meaning "palhaçada"!. The following, just for didactical purposes!
By the way, the guys involved in the polemics at the time are two very known and good soccer players of this state.
https://www.youtube.com/watch?v-NaCHHWwgA