плохому танцору и яйца мешают

Literally, "a bad dancer is impeded even by /his own/ balls". The real etymology is about eggs, not balls and goes back to the time when the German egg dance (Eiertanz), a traditional Easter game, was popular, in which eggs are laid on the ground or floor and the goal is to dance among them damaging as few as possible.

• IPA^(key): [pɫɐˈxomʊ tɐnˈt͡sorʊ i ˈjæjt͡sə mʲɪˈʂajʊt]

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плохо́му танцо́ру и я́йца меша́ют • (ploxómu tancóru i jájca mešájut)

1. a bad workman always blames his tools