Green’s Dictionary of Slang

meemies n.

also meemees, meeyams
[? var. on heebie-jeebies n.; note WWII US milit. sl. screaming meemie, the German nebelwerfer, a multi-barrelled mortar]

[1940s+] (orig. US) hysteria; usu. as screaming meemies

In phrases

screaming meemies (n.) (also screaming meamies, screaming mimis, screemies) [1940s+] (US)

1. nerves, paranoia; hysteria.

2. delirium tremens.