The Mahjong Soul online game recently launched a "Local Yaku" event with some exotic non-standard Yaku and Yakuman (see list).
Most were familiar to me but it took a little while to track down this one.
Ishinoue Nimo Sannen (石の上にも三年) is a Yakuman awarded for declaring (double) Riichi on your first discard and then finally declaring a win on the final tile of the hand (Haitei/Hōtei).
The name is also an idiom in Japanese. "Three years on the stone" - if you sit on a cold stone for three years, it will get warm. Perseverance is rewarded eventually.
It's a very appropriate name for this rare scoring combo.

Of course really I just wanted to post this cute pic with the phrase inscribed and the principle demonstrated!