It’s called, “Nutmeg Psychosis.”
In case reports intoxications with nutmeg had effects that varied from person to person, but were often reported to be an excited and confused state with headaches, nausea and dizziness, dry mouth, bloodshot eyes and memory disturbances. Nutmeg was also reported to induce hallucinogenic effects, such as visual distortions and paranoid ideation. In the reports nutmeg intoxication took several hours before maximum effect was reached. Effects and after-effects lasted up to several days.
Myristicin poisoning is potentially deadly to some pets and livestock, and may be caused by culinary quantities of nutmeg harmless to humans. For this reason, it is recommended not to feed eggnog to dogs.