Learn Turkish: Dün gece delice dans ettik. - We danced crazily last night.

deli is a word meaning "crazy". By adding the adverbial suffix -ce, it changes into an adverb meaning "crazily" or "in a crazy way". This tells us how the action happened. Because deli ends in a vowel, we just add -ce directly.

Why is the suffix -ce instead of -ca on delice?

This suffix follows two-way vowel harmony. Because the last vowel in deli is i (a front vowel), the suffix must also use a front vowel, becoming -ce. If the word had a back vowel (a, ı, o, u), it would take -ca, like in hızlıca (fast).

Doesn't dün mean "yesterday"? Why is it translated as "last night"?

You are right, dün means "yesterday". In Turkish, the standard way to say "last night" is literally "yesterday night", which is dün gece. English speakers often try to translate it directly and say geçen gece, but dün gece is the natural way to talk about the night that just passed.

Why does the verb dans ettik end in -k for "we", instead of -uz like in the present tense?

The verb here is dans etmek (to dance) in the simple past tense. Unlike the present continuous tense which uses endings like -uz for "we" (as in dans ediyoruz), the simple past tense uses the ending -k. So we take the root et-, add the past tense -ti, and finish with -k for "we", making ettik.