Ya ven ustedes, con tantos líos casi se me olvidan algunos detalles.
What does "se me olvidan" mean in this sentence, can we say " con tantos líos me olvido de algunos detalles"? Thanks a lot.
There are 2 main ideas here. 1) Reflexive verbs 2) Impersonal/passive verbs:
When you say 'Me olvidé de ponerme la ropa interior' your using reflexive verb construction in both the 'me olvidé' and 'ponerme'. If you remember from your grammar lessons (offered on this website) reflexive verbs as their name suggests, refers the action back at the subject. 'Me afeito' from the verb 'afeitar(se)' meaning to shave, means I am shaving. It's reflexive because I'm shaving myself.
The other idea of impersonal/passive verbs looks pretty much like reflexive verbs in the 3rd person.
Ref. verb in 3rd person using 'afeitarse': él se afeita, he's shaving, or for the literal translationers: él está afeitándose or él se está afeitando. The thing to note here is the 3rd person reflexive pronoun 'se' in all these examples.
Going back to the idea of impersonal/passive verbs, it uses the same 'se'. Se habla español aquí means that spanish is spoken here. Imp/pass verbs basically make a given verb state something about itself. 'Hablar' means to speak. If you only conjugate it to 'habla' that could mean he, she, it spoke. It doesn't say that something is spoken. To say that something is spoken is of a impersonal, passive nature, requiring the impersonal 'se' pronoun in front of the verb. The important thing to notice is that the impersonal 'se' pronoun looks exactly like the 3rd person reflexive 'se' pronoun, but each serves a different function grammatically.
So to answer your original question about 'se me olvida': This is utilizing the impersonal 'se' in this case. Se olvida meaning that something was forgotten. The fact that something was forgotten is attributed to the 'me' pronoun. So, something was forgotten, to me. English equivalent could be, it slipped my mind.