וְהִֽתְחַתְּנ֖וּ אֹתָ֑נוּ בְּנֹֽתֵיכֶם֙ תִּתְּנוּ־לָ֔נוּ וְאֶת־בְּנֹתֵ֖ינוּ תִּקְח֥וּ לָכֶֽם׃
און זײַט זיך מתחתּן מיט אונדז; אײַערע טעכטער װעט איר אונדז געבן, און אונדזערע טעכטער װעט איר אײַך נעמען.
Rashbam
בנותיכם תתנו ואת בנותינו תקחו לכם, the sons of Yaakov, on their part made intermarriage something that was in their honour, “i.e. to give and to take.” When Shechem and Chamor presented this proposal to their townspeople they reversed it to make it appear as if they were the ones bestowing honour, when they said: “we will take and we will give.” (verse 31) They did this in order to seduce their townsfolk to submit to circumcision.
Radak
והתחתנו אותנו, the word אותנו here means the same as if the Torah had written either עמנו or בנו, “with us.”