austeilen — to hand out. Duden gives an informal sense: to criticize sharply, as in sie kann ganz schön austeilen, she can really dish it out.
Wer austeilt, muss auch einstecken können. — Whoever dishes it out must also be able to take it.
einstecken — to pocket: to accept something without fighting back. Duden’s examples include Kritik einstecken, to take criticism.
ein dickes Fell haben — to have a thick hide, to be thick-skinned
keine Kritik vertragen — to be unable to take criticism
unter aller Kritik — beneath all criticism, very bad