Chockablock (adjective)

Crowded, packed, or filled to capacity.

Origin:

From the word "chock", meaning a block or wedge used to secure a load and the word "ablock" meaning to block or stop, together meaning completely full or packed tight.

Examples:

1. The store was chockablock with customers.
2. The train was chockablock with commuters.
3. The party was chockablock with people.
4. The park was chockablock with families enjoying the nice weather.
5. The city center was chockablock with tourists during the peak season.