Translation:This refrigerator is old.
It means old, and thinking of a tombstone is how I memorized it because that's where we're gonna end up when we're old enough
The mnemonic taught is sometimes "something that gets told many times", which helps because it looks to be made up of 十 'ten' (many, here) and 口 'mouth' (say, here). So, that's not bad to remember it by. But older versions look like a skull mask, worn in festivals to reference ancestors, and then used for 'antiquity'; eventually, 'old'; finally, simplified into '古い'。
I went to report that it didn't let me write 古い for ふるい, but the option wasn't there :-/