"Елки-палки" - это безобидное ругательство (а скорее даже - восклицание) в моменты раздражения, досады, удивления, недоумения. :)

Это эмоциональное восклицание, служащее для выражения удивления, восхищения, возмущения и иногда раздражения или злости. Эквивалентами являются, например, такие выражения, как "ё-моё!", "ёклмн!" (произносится как ё-кэ-лэ-мэ-нЭ), и "ёпрст!" (аналогично, произносится как ё-пэ-рэ-сэ-тЭ).

"Елки-палки" это означает удивление, чем-то, как правило, с негативным финалом. Разочарование чем-то и тд

Actually it’s not a frequently Occurring expression in modern Russian, it’s like outdated phrase. It’s very similar to “holy cow” or smth like that, just a kind of exclamation.

ёжкин кот. ёкарны бабай There are many such expressions starting from ё or е. Often a prolonged ёёёлки палки is implied. There are much worse phrases starting from ё or е. The innocent phrases quoted above (the point is: it must start from ё and be funny) can be interpreted in 3 ways: 1. ё became an emotional sound on its own. 2. a hint on a profanity (like "freaking"). 3. a play: you start it _as_if_ you were about to swear really badly, but then make it look like you were about to say something utterly innocent. Related facts : a) You could notice, the short form of Russian names are usually based on the stressed syllable. ВА[ня] from [и|ВАН. You also could notice, we reduce unstressed syllables (and lenghten the stressed one). In other words, the stressed syllable is important and ё- is both the initial and stressed syllable of some forms of our f-word. b) as you could guess, ёлки-палки is funny and soft enough. c) ёёёёооо.... can be interjection on its own. Usually said upon an unpleasant discovery, but can said when you're impressed by somethign good. There is a famous song "Ой-ё".