Oberkante Unterlippe
When something is so close to the limit it’s like it’s whispering 'I can’t take it anymore' to the limit.
His savings were at Oberkante Unterlippe, one more bad bet and he was broke.
The party was at Oberkante Unterlippe, one more person showed up and it was chaos.
Her tolerance was at Oberkante Unterlippe, one more swear word and she’d have exploded.