An English translation, and origin of the Hedong lion idiom.

A man of Dongpo has not one coin to his name
A decade, his homely hearth has charred lead mundane
Gold can be created, and rivers can be dammed
Yet only frost dons his temples, not to go black.

One resident of Longqiu is pitiful, too
Speaking of nothing and everything, no sleep
When suddenly, he hears his Hedong lion roar
Cane falling from his hand, he is scared stiff, speechless.

Who can resemble the uptown man of Puyang
Wining and meat-eating to self-immortalize?
Spending life in moderation, no obsession
At home, he meditates as monks not at home do.

Rice ears aplenty sway in wide fields ‘fore the gate
And clear streams wind ’round buildings and flowers endless
In a stream-abut hall, lay drunk, roused to no calls
Petals like snow, carried overhead by spring winds.

I roam about Lanxi, seeking out pure, clean springs
Having since donned dark socks and legwraps for travel
Mount Kuaiji is not without a certain old friend
I return on my drinking boat once dullness comes.

Hate, lords do, for not getting to know Yan Pingyuan
Hate, I do, for not getting to know Yuan Shanlu
On Bronze Camel Street, we will meet each other, then
Gripping hands and laughing for three-thousand years more.

Original Text
东坡先生无一钱，十年家火烧凡铅。
黄金可成河可塞，只有霜鬓无由玄。
龙丘居士亦可怜，谈空说有夜不眠。
忽闻河东狮子吼，拄杖落手心茫然。
谁似濮阳公子贤，饮酒食肉自得仙。
门前罢亚十顷田，清溪绕屋花连天。
溪堂醉卧呼不醒，落花如雪春风颠。
我游兰溪访清泉，已办布袜青行缠。
稽山不是无贺老，我自兴尽回酒船。
恨君不识颜平原，恨我不识元鲁山。
铜驼陌上会相见，握手一笑三千年。

English Explanation
For ten years, the penniless Su Dongpo — the poet — is unsuccessful at Daoist alchemy, unable to turn lead into gold. ‘Gold can be made, rivers can be dammed. If an elixir of undying can be obtained, immortals can be created, too,’ as the Historical Records, Book of Granted Zen, says, yet he grows older. A native of Longqiu, Jiangxi, who is name Chen Jichang, is having poor luck as well with insomnia, only for his overbearing wife — labeled a Hedong lion, for her surname is Liu, and Du Fu’s poem ‘Lamenting’ speaks of a woman from Hedong surnamed Liu — to roar, scaring him.
In comes the uptown man of Puyang, Wu Deren, who defied the Daoist prohibitions of drinking wine and eating meat, as well as leaving home to travel, yet reached the same end, anyways.
The narrator describes the scenery, and then visits Wu Deren, the ‘old friend on Mount Kuaiji’ — this is a reference to yet another poem, A Stanza of Remembrance by Li Bai, where ‘Mount Kuaiji has no old friend, so I row with my wine back home’, meaning that friend has died. Wu Deren isn’t dead, but the narrator didn’t visit him, either.
Yan Pingyuan is Yan Zhenqing, a beloved Tang calligrapher and politician, martyred by infamous chancellor Lu Qi; the narrator compares him to Chen Jichang. Yuan Lushan is Yuan Dexiu, Tang Magistrate of Lushan, who revitalized the community, drove out bandits, and displayed boldness; the narrator compares him to Wu Deren. Bronze Camel Gate exists outside of Gold Horse Gate, south of Luoyang Palace. It is known for having gatherings of people outside it at all times — the narrator says he will meet Wu Deren there, of all places.

Translator’s Notes
As per usual, this poem is originally in seven-character quatrains. It would be nice if using just seven syllables to complement it was possible, but with modern language being what it is, I settled with twelve-syllable verses.
Once the history behind it and the poems used in it are known, this poem really isn’t that hard to understand. Before that, though, it certainly is. Oof…