On Facebook, liking something some one shared, sharing it, then when some one else shares it from you, liking it again.
You may or may not have liked the shared thing on your own profile, but the word has more meaning when you do not like the shared thing in your profile. One shares something on their profile when they like it. Therefore, it is redundant to like it via the like button on their profile.
Could be used in the past tense as "cross-liked".
Anne shared a link to a new music video. I liked it and shared it on my profile. Then Peter liked and shared the video from my profile. So I went to his profile and liked it. Then pretty much all my friends started sharing the link and I went on a cross-liking spree and cross liked every time the link was shared.