In Spanish, there's the expression ¡no escupas para arriba! (literally ‘don't spit upwards!’), which is used for example in counter-reprimanding or counter-criticizing purposes—although there are many contexts where it could be used. I don't think it's easy to give a definition but I think this description is good:
Se trata de una expresión de ámbito universal, como lo demuestra su presencia en otras lenguas, que funciona a modo de máxima admonitoria. En tal sentido, puede emplearse en distintas situaciones. Las más comunes sugieren y ponen en guardia a quienes se burlan o regocijan de la adversidad ajena; o bien a quien proclama temerariamente opiniones, juzga y critica a otros por sus errores. Todas ellas exhortan a ser cautos y no hablar más de la cuenta porque el infortunio puede recaer en quien se muestra despiadado con los demás, al poder verse arrastrado a una situación similar. Porque, como señala otro dicho antiguo, «la vida da muchas vueltas» y «nunca se puede decir de esta agua no beberé».
[...]Lo que carece de valor y se repudia (el «escupitajo»), se arroja contra quien es objeto de ultraje, aunque sin ser consciente de que «le puede caer a uno encima». Y esta interpretación asoma en un sustrato subliminal de la actitud de quien critica, habla mal de alguien, se burla o le denigra de algún modo.
[...]Una expresión cercana a esta es la que dice: «Lo que se siembra, se recoge»[...]; aunque esta frase puede tener un significado ambivalente [bueno o malo].
En última instancia, el significado profundo del refrán «no escupas para arriba porque te puede caer encima» [...] está ligado a una especie de principio retributivo universal que se expresa en que todo mal que provocamos, tarde o temprano, se nos vuelve en contra y nos retorna.
My translation:
It is an expression with universal scope, as is confirmed by its presence in other languages [English too?], which works as a maxim of admonishment. With this sense, it could be used in many situations. The most frequent warn and raise the guard from those which taunt or brag from the other's adversity; as well as from those who boldly proclaim opinions, judge and criticize others for their mistakes. All of them exhort to be cautious and to not speak more than necessary because misfortune could recur in those who are ruthless with the others since they could be ‘plunged’ in a similar situation. For, as it is stated by another old saying, «life has many turns» and «under no circumstance can be said: "from this water I shall not drink"»
What is despised, i. e., that which lacks value and is repudiated (the "spit"), is thrown towards who is the outrage target, although without being aware that "it may fall on the spitter's head". And this interpretation appears on a subliminal substratum in the attitude of those who criticize, speak ill of someone, mock or denigrate them in any manner.
An expression that is close to this one is the one which says: "What you sow, you reap"; although this sentence may have an ambivalent meaning [could be something either good or bad].
Ultimately, the authentic meaning of the saying "don't spit upwards because it may fall on you" is associated to a kind of universal retributive principle which expresses that all the harm we cause, sooner or later, will be turned against and come back to us.
As I understand, the author claims that the expression is universal so: Can I say ‘don't spit upwards!’? I found one expression which is ‘What goes around, comes around’; do you think that expression is an equivalent? Do you use it in the same context? If not, which expression is the first you think as an English equivalent when you read the paragraph?
APPENDIX Examples of usage
A: —Don't you think it's funny how X was kicked off from school just because he was caught up cheating in an exam? I bet his dad will lash him!
B: —¡No escupas para arriba! (i. e., it could also happen to you)
A: —B, I can't let you sit in my car. I'm intransigent with my principles and you know well that I don't allow any <put any ethnical group you'd like> in my car.
B: —¡No escupas para arriba! (i. e. someday you will ask me to take you in my car)
A: —I hate X's boy/girlfriend, (criticizing process...). I will ask them to not come to my house again
B: —¡No escupas para arriba! (i. e. who says that tomorrow they could not be your fiancé, too?)
