My grandfather once asked me, if I knew a word with three "e" in a row. I couldn't think of any. He told me that the word was длинношеее, long-necked (neutral form). I didn't believe it and had to write it down to see for myself :).
It's made from длинный (long) and шея (neck). Masculine form is длинношеий, feminine - длинношеяя.
For example, длинношеее животное — long-necked animal
or длинношеее создание — long-necked creature.
Does your mother tongue have words with three of the same letter in a row? Let me know in the comments!